"Six goals against Chelsea isn't easy".
Spotting Aguero on the field after the final whistle, Dean tucked the bright yellow ball up the back of his black referee's jersey.
He made an encouraging start to his tenure as Chelsea were unbeaten after their first 12 Premier League matches under him this season, but they have faded out of title contention and now face a battle to finish in the top four.
"All I can do is apologise to the fans because it is not acceptable", he said.
"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. Standing between Chelsea and the League Cup is City in the final on February 24 at Wembley Stadium.
"City have had their rollicking off their manager and they've had their points dropped".
City boss Pep Guardiola empathises with his counterpart, pointing to his own occasional difficulties in implementing his ideas when he first arrived in the north-west three years ago.
It began badly as they were caught napping after just four minutes.
USA heightens attacks on Taliban to gain leverage in peace talks
The former president also said that it is the Afghan people, who should decide whether any foreign military bases should stay on the territory of Afghanistan.
Guardiola had left David Silva on the bench but his midfield looked perfectly balanced with De Bruyne and Gundogan providing a presence in the middle and Bernardo Silva, who seems to get better with every game, in imperious form on the right flank.
Before starting on his way to another hat trick, Aguero uncharacteristically missed the target from close range.
'To be honest, I don't know what to expect. "But, after, his reaction was a little bit better".
Not a bad 65-minute run out for the in-form forward, who took his tally to 23 for the season and made it nine goals in his last six outings.
"So at some point you've got to change what you're doing".
It was Chelsea's heaviest defeat since losing 7-0 to Nottingham Forest in 1991.
He added: "It was an incredible performance against a top team". But on the hour, Leicester was awarded a penalty when defender Jan Vertonghen knocked over James Maddison.
Pochettino's side took the lead through Davinson Sanchez's first goal for the club, but they were indebted to Hugo Lloris for saving Jamie Vardy's spot-kick after the interval at Wembley.