Turin - Juventus's Champions League hopes are hanging on Cristiano Ronaldo pulling off another sensational comeback as the Italians trail 2-0 to defensive specialists Atletico Madrid going into the last 16, second-leg tie in Turin on Tuesday.

"We didn't expect to lose the first leg 2-0, but anything can happen, and we want to give a great response in our home, in front of our fans," Ronaldo told Juventus TV ahead of the game in the Allianz Stadium.

"These are the great nights, the fantastic ones: the Champions League nights," he continued. 

"The team is confident of playing a great game and I am too. To the fans I say: think positive, let's believe.

"Get ready to come back!"

The seven-time reigning Italian champions bought Ronaldo last summer from Real Madrid for €100 million ($117 million) to end their Champions League heartbreak going back 23 years.

The 34-year-old's stunning overhead kick for Real in the quarter-finals in Turin last April had dumped Juventus out of the tournament once again.

Expectations are high that he can reproduce his improbable hat-trick which lifted Real Madrid past Wolfsburg in April 2016 with the Spaniards 2-0 down to the Germans after the first leg.

Juventus have come from behind in the elite European competition eight times -- including in the 1996 quarter-finals against Real Madrid on their way to winning the title.

They also lifted the European trophy in 1985, but have finished runners-up five times since their last success, including twice in the past four years.

Years of disappointments

"CR7 is here for that," wrote Italian sports daily Corriere dello Sport, of "a game Cristiano cannot get wrong."

"He wasn't signed to win the Scudetto or to boost merchandising, Juve are waiting to end years of disappointments."

Ronaldo won five Champions League titles with Manchester United and Real Madrid and has scored a record 121 goals of which 57 have proved decisive.

The top scorer in the Champions League for the last six seasons, he has however scored just once in this year's competition, delivering a performance far below expectations in Madrid.

Since the Madrid game he has not scored in the league and has been overtaken as the top Serie A scorer by Sampdoria's Fabio Quagliarella, who has 20 goals to Ronaldo's 19.

The problem for Juventus is they need to score at least twice against a team that specialises in defence.

Diego Simeone's Atletico -- second in La Liga -- have not conceded a goal for five games. 

"Everyone knows that they are a strong team, they defend very well, they don't take a lot of risks and they play on the counter-attack, but we are ready, and we will do everything we can to beat them," said Ronaldo, who has scored 22 goals against Atletico. 

"The fine details will make the difference, and we want to win and qualify for the quarter-finals."

High stakes

Former-Wolfsburg manager Dieter Hecking believes Ronaldo can make a difference.

"Ronaldo is capable of everything, he can also score three goals again as he did against my Wolfsburg. Of course he can," Hecking told Gazzetta Dello Sport.

"Atletico have the best defence in Europe and an excellent attack: without Ronaldo, who can invent goals in any way, it would be impossible.

"If I said that Ronaldo is not the strongest player I have ever met, I would lie.

"I remember that night I told the team that we should not be afraid neither of him nor the Bernabeu, but at 17 minutes we were already 2-0 with a double by CR7, it was monstrous."

Allegri's future at the club he has won 10 trophies with since 2014 will likely hinge on this game. The Juventus coach knows the stakes are high.

"I think expectations have been raised far too much and it has become an obsession," said the 51 year-old.

"Since I arrived, the Champions League has always been an objective, but if people say that it's a failure if Juventus go out, that is not right."