Pep Guardiola fears Manchester City's come-from-behind victory over Chelsea may have come at a cost after striker Sergio Aguero limped off in the second half.
The Argentinian was replaced by Gabriel Jesus with 13 minutes left, one of three enforced changes for City on a night when first-half goals from Kevin De Bruyne and Riyad Mahrez gave them a 2-1 win after N'Golo Kante put Chelsea in front.
Aguero's problem comes ahead of Tuesday's Champions League match against Shakhtar Donetsk, and with trips to Newcastle and Burnley on the horizon before the Manchester derby on December 7.
"We will see tomorrow but it doesn't look good," Guardiola said of Aguero. "I think it's muscular...
"He thought it was a kick but maybe he stretched it a bit."
Aguero came off after City had already lost Spanish midfield duo Rodri and David Silva to cramping problems which looked less serious.
"Rodri has been one month without playing many games and David, he needs rhythm and these games are so demanding," Guardiola said.
It certainly looked a demanding match as two teams with problems at the back decided attack was the best form of defence.
The result was at times a pulsating encounter, edged by City as they moved back above Chelsea and into third place.
Chelsea showed the confidence of a team who had won six in a row in the Premier League coming into this match, while City demonstrated the desire of a side desperate to bounce back from their defeat at Anfield a fortnight ago.
The visitors drew first blood when Kante burst through City's defence, in which Fernandinho partnered John Stones, to slip the ball beyond Ederson after 21 minutes, and the hosts needed a deflection on De Bruyne's shot to level eight minutes later.
Mahrez then produced a moment of real quality just before the break, cutting inside from the right, ghosting between Emerson and Mateo Kovacic before firing between Fikayo Tomori's legs and in.
At the time it seemed unlikely to be the winning goal – Aguero would hit the crossbar while shots whistled narrowly wide at both ends and Raheem Sterling had a stoppage-time effort scrubbed out for a tight offside – but City held out for victory.
"We won against a top side," Guardiola said. "Chelsea over the last 20 years have always been a good team but Frank is a courageous manager."
That courage was shown in the amount of time Chelsea had City on the back foot. The visitors limited City to 46.7 per cent possession, the lowest total of any Guardiola-managed side in his 381 top-flight matches to date, but ultimately could not make it count.
"It was not the critical factor," said Lampard. "Coming into the game, with our recent form and how we've been developing quickly, I wanted to come and be brave on the ball and off the ball.
"In the first half you saw all of that and at 1-0 we had relative control of the game, but that never lasts.
"There were a lot of positives but we lost the games. It shows at this level it's the finer details in both boxes that decide it.
"These teams, Liverpool and City, have been getting results for a long time because these finer details, maybe they get them right.
"I don't think you can come away from that game and say it was anything other than two really strong teams going against each other.
"One wins it because of a deflected goal and a really good goal, and the rest was in the balance."
