The Champions League is back, and back with a bang, after the draw for the 2020-21 group stage concluded on Oct. 1 in Geneva. The top line? A head-to-head between Cristiano Ronaldo and Lionel Messi as Juventus and Barcelona were paired together in Group G, in a game that could also see fans inside the stadium after UEFA confirmed grounds can be up to 30% full for fixtures if local regulations permit.

The standout pairing of the group stage also boasts an American subplot, with U.S. teammates Weston McKennie and Sergino Dest facing off against each other.

Matchday 2 gives us the first of two blockbuster group stage matches between Juventus and Barcelona, though it's unclear as yet whether Ronaldo will suit up given his recent positive tests for the coronavirus.

Elsewhere, you've got Atletico Madrid looking to rebound from a heavy defeat to Bayern Munich in Group A, Manchester City and Pep Guardiola hoping to break their slump at Marseille in Group C, Ajax traveling to Atalanta in a Group D match with plenty of knockout-round implications, and a chance for Chelsea to end their own scoreless streak in a trip to Krasnodar in Group E. Dortmund and Real Madrid, two of the stronger teams in this year's competition, are also hoping to shrug off shock defeats to Lazio and Shakhtar Donetsk in Matchday 1 and get into the wins column.

Editor's note: This has been updated since the group stage draw concluded on Oct. 1 in Geneva. Expanded group stage analysis of Matchday 2 is by Tom Hamilton.

GROUP A: Bayern Munich, Atletico Madrid, RB Salzburg, Lokomotiv Moscow

Tuesday, 1:55 p.m. ET/5:55 p.m. GMT

Reigning champions Bayern Munich travel to Moscow off the back of a storming 5-0 win over Eintracht Frankfurt at the weekend. Robert Lewandowski scored yet another hat-trick to make it 10 goals in five league games for the season, while Leroy Sane and youngster Jamal Musiala also scored. Having won their opening Champions League group match against Atletico Madrid 4-0 last week, Bayern are rumbling along nicely but will be without left-back Alphonso Davies, who picked up an ankle injury on Saturday.

Lokomotiv drew 2-2 at RB Salzburg in their first Group A match and lost at home 2-1 to Rotor on Saturday, with Grzegorz Krychowiak sent off. It was a poor result given that Rotor are firmly at the wrong end of the Russian Premier League table; Lokomotiv won't have it easy against Bayern on Tuesday night. Expect a comprehensive win for the German side.

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Tuesday, 4 p.m. ET/8 p.m. GMT

After they were hammered in the opening round 4-0 at Bayern, the only way is up for Diego Simeone's men. They will come into this buoyed by their 2-0 win over Real Betis on Saturday in which Marcos Llorente and Luis Suarez scored, but they will likely be without Diego Costa and Saul Niguez for Tuesday.

Salzburg are tearing it up in the Austrian Bundesliga and won 2-0 on the road at Austria Wien on Saturday courtesy of goals from Mergim Berisha and Patson Daka. They are without long-term absentee Antoine Bernede and will do well to claim anything from an Atletico team that can pick apart most opponents.

GROUP B: Real Madrid, Shakhtar Donetsk, Inter Milan, Borussia Monchengladbach

Tuesday, 1:55 p.m. ET/5:55 p.m. GMT

Shakhtar pulled off the biggest shock of Matchday 1 when they won 3-2 at Real Madrid with Tete and Manor Solomon both scoring alongside a Raphael Varane own goal. It was a remarkable performance from Luis Castro's side, but they stuttered at home to Vorskla in a 1-1 draw at the weekend despite playing against 10 men for 37 minutes.

Antonio Conte's Inter drew 2-2 with Borussia Monchengladbach in their Champions League Group B opener but got back on track away at Genoa on Saturday with Romelu Lukaku and Danilo D'Ambrosio scoring in their 2-0 win. They have Ashley Young, Milan Skriniar and Alexis Sanchez all out. This has "tense draw" written all over it.

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Tuesday, 4 p.m. ET/8 p.m. GMT

Borussia continue to play their way into form this season, winning 3-2 at Mainz with Lars Stindl, Jonas Hofmann and Matthias Ginter all scoring. They sit fifth in the Bundesliga and are still without Denis Zakaria for Tuesday's match against an unpredictable Real Madrid.

Real won 3-1 at Barcelona on Saturday in the first Clasico of the season with Federico Valverde, Sergio Ramos and Luka Modric all scoring. But their big team news sees Eden Hazard return to the squad while there are question marks over who plays at right-back with Dani Carvajal, Alvaro Odriozola and Nacho all injured. Ferland Mendy could deputise there, or they may opt for Lucas Vazquez, who played well at right-back after coming off the bench on Saturday.

It promises to be a cagey affair in Germany, but Ramos & Co. have enough class to rebound given that they can't afford to lose any more ground after Matchday 1's shock defeat.

GROUP C: FC Porto, Manchester City, Olympiakos, Marseille

FC PORTO vs. OLYMPIAKOS
Tuesday, 4 p.m. ET/8 p.m. GMT

Porto lost 3-1 at Manchester City last week, but managed to get a key 1-0 win across the line against Gil Vicente on Saturday thanks to Evanilson's goal, having been reduced to 10 men for the final 16 minutes when Zaidu Sanusi was red-carded.

Olympiakos got their Champions League campaign off to a superb start, beating Marseille 1-0 thanks to Ahmed Mahgoub's injury-time winner. They had the weekend off so will be fit and firing for their trip to Lisbon. We're rooting for a shocking away win in this one.

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MARSEILLE vs. MAN CITY
Tuesday, 4 p.m. ET/8 p.m. GMT

Andre Villas-Boas' Marseille side won 1-0 at Lorient on Saturday thanks to Leonardo Balerdi's goal and have a fully-fit squad for when they welcome Pep Guardiola's side on Tuesday evening.

Manchester City's stuttering start to the 2020-21 season (by their high standards, at least) continued when they drew 1-1 at West Ham on Saturday, with substitute Phil Foden scoring the equaliser. Guardiola is under increasing pressure to make a decision on where his future lies with his contract up in eight months' time, and his side will travel to France without Fernandinho (who was injured against Porto), Aymeric Laporte, Benjamin Mendy and Gabriel Jesus.

You wouldn't bet against the visitors taking all three points, but Marseille have the nous to exploit what's wrong with Man City at the moment.

GROUP D: Liverpool, Ajax, Atalanta BC, FC Midtjylland

ATALANTA vs. AJAX
Tuesday, 4 p.m. ET/8 p.m. GMT

Atalanta trounced Midtjylland 4-0 on Champions League Matchday 1, but that triumph is sandwiched between two heavy defeats in Serie A. They lost at home 3-1 to Sampdoria on Saturday, which followed their 4-1 defeat at Napoli the previous week. Gian Piero Gasperini's side will look to get back to winning ways against Ajax but will not have it easy against the record-breakers.

Ajax won 13-0 at VVV-Venlo on Saturday, a record triumph in the Eredivisie with Lassina Traore scoring five and Jurgen Ekkelenkamp and Klaas-Jan Huntelaar both grabbing braces. Having lost 1-0 at home to Liverpool in the opening round, the Dutch giants know they'll need a win on the road at Atalanta to keep their Champions League prospects alive. However, they will be without new signing Mohammed Kudus, who picked up a nasty injury last week.

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All signs point to Atalanta emerging on top.

Tuesday, 4 p.m. ET/8 p.m. GMT

Jurgen Klopp's men continue to find their way without talismanic defender Virgil van Dijk but will take heart from their 2-1 win over Sheffield United at Anfield on Saturday in which Roberto Firmino opened his account for the season and Diego Jota scored the winner. Goalkeeper Alisson returned at the weekend but the Reds will be without Joel Matip, Thiago Alcantara and Naby Keita this week.

Midtjylland will be massive underdogs for their trip to Anfield and will be without Jesper Hansen and Junior Brumado. But they won 3-2 at Brondby at the weekend with Anders Dreyer and the brilliant Pione Sisto both scoring, with their late winner coming courtesy of Marvin Schwabe's 94th-minute own goal.

All in all, we're picking a nervy but comprehensive home win for the Reds.

GROUP E: Sevilla, Chelsea, Krasnodar, Rennes

KRASNODAR vs. CHELSEA
Wednesday, 1:55 p.m. ET/5:55 p.m. GMT

Russian side Krasnodar earned a credible 1-1 draw at Rennes in their Group E opener, but are still mid-table in the Russian Premier League having lost at home 3-1 to Spartak Moscow on Saturday -- a match that saw Alyaksandr Martynovich sent off.

Chelsea have gone two matches without a goal, having drawn 0-0 against Sevilla in the opening round and again at Manchester United on Saturday. But apart from absentees Kepa Arrizabalaga and Billy Gilmour, they have a fully-fit squad so expect to see more of their summer signings adjust to life under Frank Lampard.

This should be a game that gets them into the win column for the first time in this nascent Champions League 2020-21 campaign.

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SEVILLA vs. STADE RENNES
Wednesday, 4 p.m. ET/8 p.m. GMT

Sevilla's point at Stamford Bridge on Matchday 1 could prove essential in the eventual shakedown of the group but they will need to pick themselves up after a surprise 1-0 defeat at home to Eibar at the weekend. And they'll be without defender Jules Kounde -- who's on Manchester City's radar -- due to COVID-19.

Rennes would have hoped for better than a 1-1 draw in their opening Champions League game, and they slumped to a 2-1 defeat at home to Angers on Friday, so they'll have to dust themselves down for the trip to Spain on Wednesday. They are still without Faitout Maouassa and M'Baye Niang.

Expect Sevilla to claim all three points given their wealth of experience in Europe.

GROUP F: Zenit St. Petersburg, Borussia Dortmund, Lazio, Club Brugge

CLUB BRUGGE vs. LAZIO
Wednesday, 4 p.m. ET/8 p.m. GMT

Club Brugge's impressive 2-1 win on the road against Zenit in Round 1 was tempered by their 2-1 defeat at Leuven on Saturday. Noa Lang's first-half penalty was not enough to see them home, and they'll have to improve against a Lazio side who will be buoyed by their 3-1 win over Borussia Dortmund in the opening round in Europe and their 2-1 win at Bologna on Saturday, where Luis Alberto and Ciro Immobile scored.

Lazio will be without Stefan Radu, Silvio Proto and Senad Lulic while Club Brugge have Simon Mignolet doubtful due to COVID-19 test results. All signs point to an away win.

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Wednesday, 4 p.m. ET/8 p.m. GMT

Dortmund took the Revierderby bragging rights on Saturday in a 3-0 win over Schalke, with Manuel Akanji, Erling Haaland and Mats Hummels all scoring. But they are without Emre Can for Wednesday's match due to Covid-19 while Marcel Schmelzer and Dan-Axel Zagadou are also absent. They desperately need a win after losing in Rome to Lazio last week.

For Zenit, they too urgently need to get their campaign back on track after their surprise opening-round defeat to Club Brugge and their 2-1 defeat at the weekend to Rubin Kazan would not have helped. Douglas Santos is banned for Wednesday's match while Malcom is still out injured.

Given that both teams need the points, we're picking Dortmund in a breezy, end-to-end affair.

GROUP G: Juventus, Barcelona, Dynamo Kiev, Ferencvaros

Wednesday, 4 p.m. ET/8 p.m. GMT

The Hungarian side Ferencvaros felt the full force of Barcelona in the opening week as they lost 5-1 at Camp Nou. But they dusted themselves down for Saturday's match against Ujpest where they won 2-0 thanks to goals from Tokmac Nguen and Somalia, with Abraham Frimpong seeing red.

Dynamo Kiev lost at home to Juventus 2-0 in the first round of matches and narrowly edged past Oleksandriya 1-0 on Saturday with Mykola Shaparenko getting sent off. We expect Kiev to prove too good for their hosts.

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JUVENTUS vs. BARCELONA
Wednesday, 4 p.m. ET/8 p.m. GMT

This is the match of the round, with everyone keeping fingers crossed we will see Cristiano Ronaldo coming up against Lionel Messi. Ronaldo's availability is dependent upon medical clearance following his positive COVID-19 test result last week -- he needs to return a negative result 24 hours before kick-off on Wednesday night to be allowed to play. Without Ronaldo, Juventus laboured to a 1-1 draw at home to Verona on Sunday with Dejan Kulusevski's goal securing the point.

Andrea Pirlo was less than impressed with his side, saying the result should serve as a "slap in the face." They are likely to also be without veteran Giorgio Chiellini, Matthijs de Ligt and Alex Sandro.

Barcelona fell to fierce rivals Real Madrid on Saturday at Camp Nou and will be desperate to make amends for that Clasico defeat on the road at Juventus. Messi's fit but they are without Samuel Umtiti and Coutinho, while Marc-Andre ter Stegen is also likely to be absent. Gerard Pique also misses out through suspension but they have Jordi Alba available again after his recovery from injury.

This one could genuinely go either way, but maybe Barca will be appropriately steeled following the weekend letdown to take points from their trip to Turin.

Wednesday, 1:55 p.m. ET/5:55 p.m. GMT

The Turkish side lost at RB Leipzig 2-0 in the opening round thanks to Angelino's double, but bounced back in style against Antalyaspor at the weekend, winning 5-1 with Edin Visca's double helping them to a comfortable victory. Okechukwu Azubuike is a doubt for Wednesday's clash against the Ligue 1 champions.

PSG have a growing injury list with Idrissa Gueye, Leandro Paredes, Marco Verratti, Mauro Icardi, Thilo Kehrer and Juan Bernat all injured and they'll still be smarting from their defeat to Manchester United in Round 1. But their 4-0 win over Dijon on Saturday would have helped with Moise Kean and Kylian Mbappe both scoring twice.

You'd be hard pushed to pick PSG to labour again, but they're not the force they were at the tail-end of last season's Champions League campaign -- at least not yet.

MAN UNITED vs. RB LEIPZIG
Wednesday, 4 p.m. ET/8 p.m. GMT

United's mixed start to the season continued at the weekend as they drew 0-0 at Old Trafford with Chelsea, but while their Premier League form is underwhelming they had a perfect start in the Champions League thanks to their 2-1 win at PSG last week. They are without Eric Bailly and Jesse Lingard for Wednesday's game, while Donny van de Beek continues to see his involvement limited to a few minutes off the bench.

Leipzig have enjoyed a great start to the 2020-21 campaign. They are undefeated in the Bundesliga and won 2-1 against Hertha Berlin at the weekend, with Dayot Upamecano and Marcel Sabitzer both scoring. They also made a perfect start to their Champions League campaign, beating Istanbul Basaksehir, and will hope for more of the same at Old Trafford on Wednesday but will likely be without Tyler Adams, Nordi Mukiele, Marcel Halstenberg, Konrad Laimer and Lukas Klostermann.

United need to be robust at home, but Leipzig are undoubtedly the form team heading into Wednesday's game.