Manchester City boss Roberto Mancini saw rusty Carlos Tevez trigger the fightback which earned a 2-1 win over Chelsea but it was matchwinner Samir Nasri who he implored to find better form.
Nasri has struggled to justify his £24million transfer fee since moving north from Arsenal in the summer.
The French midfielder came good just when Mancini needed him to last night, running onto Tevez's deft pass to score the winner five minutes from time that cut Manchester United's lead at the top of the table to a single point.
But Mancini is a hard taskmaster. And he believes Nasri can do much more.
"Samir did well but he can do better," said Mancini.
"He can improve. He is a top player. If he plays like this he can be like David Silva or Xavi if he plays."
Yet Nasri was overshadowed by Tevez, who ended his six-month exile by inspiring City's comeback after they had fallen behind to Gary Cahill's deflected opener.
It is clear Tevez could now play a huge part in determining where the title ends up, although Mancini has pleaded for patience.
"Carlos is not 100% but that is normal," said Mancini.
"But he knows football. That was important because he did an incredible assist for Samir.
"What happened with him finished one month ago when Carlos came back and everything was finished.
"I have spoken to Carlos every day in the last month.
"He knew he would be on the bench today and would probably play for 20 minutes.
"If he can find good form in 10 days or two weeks, that would be important for us.
"Now he needs to play some games, for us, him and his future."
Mancini hopes skipper Vincent Kompany will recover from a calf strain in time to face Stoke on Saturday but Joleon Lescott has already been ruled out with a hip complaint.
Chelsea's first defeat under Roberto Di Matteo dealt a blow to their hopes of securing a top-four finish to squeeze into next season's Champions League.
"It is a setback for us but we look forward to the future," said Italian Di Matteo.
"Two weeks ago we were seven points behind third place, now we are six.
"We need to look at these things because we are going in the right direction."
Di Matteo had no complaints about the handball decision that went against Michael Essien that allowed Aguero to equalise.
And he defended his decision to select Fernando Torres ahead of Didier Drogba, even though the £50million Spain striker did not look too impressed to be replaced by the Ivorian in the late stages.
"I just thought that for the dynamic of the team it was going to be the right decision," said Di Matteo.
"No player is happy to be taken off but there is absolutely no problem with that."