The Italian watched on in horror as his side Chelsea side conceded four goals inside the first half an hour.
City added two more goals in the second half, rounding off a horrid afternoon for the west London side.
And as Mike Dean blew the full-time whistle, Sarri couldn’t exit the Etihad turf fast enough, storming straight down the tunnel.
Guardiola walked towards the Chelsea boss, hand out-stretched, waiting to speak to him after the clash.
But the Spaniard was left to speak to assistant Gianfranco Zola as Sarri hastily marched down the tunnel.
The Chelsea chief didn’t appear to see Guardiola as he walked past but the City boss was still left shocked by his opposite number’s behaviour.
“Sarri not shaking hands is a joke, embarrassing result!” said one fan.
“Sarri walks down the tunnel and does not shake Guardiola’s hand. He’s breaking down,” another said.
“Maurizio Sarri refuses to shake any hands at final whistler and walks straight down tunnel. Latest reports say he kept going and is currently walking back to Italy,” added a third.
Sarri is now facing calls from the Chelsea faithful to leave the club after only seven months in charge at the helm.
The Blues have now dropped to sixth position in the league.
Today’s defeat was the club’s worst since the Premier League began.