Chelsea, on the other hand, have plenty to think about as they try and challenge for the top four. Five players have each scored hat-tricks for three different clubs: Yakubu (Blackburn Rovers, Everton and Portsmouth); Nicolas Anelka (Arsenal, Chelsea and Manchester City); Kevin Campbell (Arsenal, Everton and Nottingham Forest); Les Ferdinand (Newcastle United, Queens Park Rangers and Tottenham Hotspur) and Teddy Sheringham (Manchester United, Portsmouth and Tottenham Hotspur).
"It was not easy because Chelsea demanded a lot and we defended deeper, like never before, because they have the quality to find spaces".
A poor header by Chelsea's Ross Barkley towards his own goal gifted Aguero with City's third, the Argentine firing home with a first-time shot on the turn, and then a low drive from Ilkay Gundogan made it 4-0 after 25 minutes.
Guardiola's side retained first place in the league table and Cesar Azpilicueta described it as one of the worst days of his career. "It is hard to explain what happened", said Chelsea captain Azpilicueta. "All I can do is apologise to the fans because it is not acceptable".
Sarri was also asked if he feared for his future as Blues boss.More news: Chelsea’s Kante Could Be PSG Target
"I'm worried about my team, I'm worried about the performance, [but] my job is always at risk, so I'm not worried about that", Sarri said. "You are asking me [about] something which is not my job".
I had called a couple of Chelsea performances a disgrace going into this game, this is as bad as anything. You'd have to ask the club. "That is quite similar, but I don't want to compare". The only reason I came to City, the chairman and the people here, they believe in me and don't think badly when I lose. The Merseysiders' game in hand is away to a rejuvenated Manchester United on February 24 - the same day City face Chelsea in the League Cup final. They have since lost seven out of 21 in all competitions.
"At the beginning we played better away than at home, now we play better at home, so something has changed and I am not able to see the reason, so I have to work for this", Sarri continued.
"People don't understand how hard the first year can be". We started well but after four minutes we conceded a goal in a stupid way.
But the Catalan coach need not have anxious that would prove a costly miss as Aguero made amends in stunning fashion by blasting into the top corner from 25 yards to double City's after just 13 minutes.