The video official spent more than three minutes analysing whether Nicolas Otamendi had handled a long-range shot from Daniel Caligiuri after a corner had initially been given.

Replays as to whether handling was intentional seemed inconclusive and the referee was unable to review himself because the pitchside monitor was broken, but a spot-kick was still given and Otamendi booked.

Nabil Bentaleb converted and did so again moments later after a foul by Fernandinho, while Otamendi's frustrations were compounded when he was sent off for a second bookable offence in the second half.

Debate raged afterwards but City manager Pep Guardiola at least tried to defuse any tensions.

"It's a penalty," Guardiola said. "I'm a big fan of VAR. The second one is a penalty too.

"It was offside too – so, if we complain about VAR maybe it was offside, but it was a penalty and the red card can be a red card.

"VAR needs time. Next time it will be better."

Guardiola was pleased with the result at the Veltins Arena, which puts City on course for the quarter-finals, but it proved much harder work than expected and highlighted some shortcomings.

That led to the Spaniard again questioning whether quadruple-chasing City, one of the competition favourites, were good enough to challenge for the trophy.

He said: "The result is incredible, three goals away, but we gave away the goals and the red card.

"In this level we don't have a chance. Still we are not ready to fight for the Champions League.

"After the red card maybe if they'd pushed more and scored a third or fourth then maybe we're out.

"It is not over. Hopefully our fans can help us in the second leg and hopefully we can improve for the future."

Sterling told BT Sport: "It was a really tough game. We made it difficult for ourselves at times but we stuck together, even with 10 men."

ga('create', 'UA-72310761-1', 'auto', {'name': 'pacontentapi'});
ga('pacontentapi.set', 'referrer', location.origin);
ga('pacontentapi.set', 'dimension1', 'By Andy Hampson, Press Association Sport, Gelsenkirchen');
ga('pacontentapi.set', 'dimension2', 'a14f2c63-4b48-4baa-9def-1c08b4925043');
ga('pacontentapi.set', 'dimension3', 'paservice:sport,paservice:sport:club-news,paservice:sport:football,paservice:sport:uk,paservice:sport:world');
ga('pacontentapi.set', 'dimension6', 'story');
ga('pacontentapi.set', 'dimension7', 'composite');
ga('pacontentapi.set', 'dimension8', null);
ga('pacontentapi.set', 'dimension9', 'sport:football');
ga('pacontentapi.send', 'pageview', { 'location': location.href, 'page': (location.pathname + location.search + location.hash), 'title': 'Guardiola warns City \u2018don\u2019t have a chance\u2019 if Schalke errors are repeated'});