Gelsenkirchen - Manchester City staged a fine fightback from 2-1 and a man down to beat Schalke 3-2 in Germany on Wednesday and take a huge step towards the Champions League quarter-finals.

The Premier League leaders had to work harder than imagined against a Schalke side languishing 14th in the Bundesliga as two Nabil Bentaleb penalties gave the hosts a 2-1 half-time lead after Sergio Aguero's early opener.

Nicolas Otamendi was then sent off to leave Pep Guardiola's men down to 10 men, but former Schalke favourite Leroy Sane's brilliant free-kick levelled for City before Raheem Sterling completed the comeback in stoppage time.

Here are three things we learned from a dramatic night at the Veltins Arena:

VAR issues remain

VAR had its first big night in the Champions League and not for all the right reasons with long delays over the decisions to award City's opener and the controversial first penalty that got Schalke back in the game.

Spanish referee Carlos del Cerro Grande took an age to finally point to the spot and it was hard to argue he had made a clear and obvious error when deciding Otamendi had not deliberately handled inside the area in the first instance.

Sane sucker punch

Schalke looked set for a massive upset until the man they formed came off the bench to ride to City's rescue.

Sane came through Schalke's academy before joining the Premier League champions in 2016.

The German international had to wait to make an impact as he was left on the bench by Guardiola, as has often been the case this season.

But the 23-year-old possesses game-changing ability and his free-kick five minutes from time swung the game and tie back in City's favour.

Late show saves more away day blues

Guardiola had to face questions before the match on his inability to win the Champions League since leaving Barcelona, where he won the competition twice in four years in charge.

The root cause of Guardiola's failure to lift the trophy in three years at Bayern and so far in his third season at City is a consistent struggle on the road in knockout games.

This was just a second win for Guardiola's sides in their last 12 away games from the last 16 onwards.

The Catalan coach's decision to drop Fernandinho into the back four alongside Otamendi, with his best centre-back Aymeric Laporte again switched to left-back, backfired.

If Otamendi's first yellow card for the handball leading to the first penalty was harsh, the Argentine stupidly got himself sent off with a second booking and Fernandinho is also banned for the second leg after picking up a yellow card.

The star power of Sane and Sterling saved the day, but City will need to be much better on the road in tougher tests to come if they are to win the Champions League for the first time.