A decision that has led the Blues to struggling in their last three away Premier League matches in the last two weeks.
Defender Azpilicueta, who was given a torrid time by two-goal City winger Raheem Sterling, said on the club's website, chelseafc.com: "It's hard to find the words to describe my feeling after the game". This string of games is especially tricky given the fact that the other club battling for the top spot in the Premier League, Liverpool, only has four games with fewer stakes than City.
ZInedine Zidane is also available right now and comes off the back of three consecutive Champions League wins.
"It is one of the worst nights in my career".
"Sometimes you can win games not playing your best".
Both players' form will play a great part in deciding the fate of the title at the end of the season.
The Europa League takes on added significance for Sarri, as the club could very well miss out on the Champions League qualification via the Premier League for a second year running, but Europe's secondary competition could provide a backdoor to the competition.
Blues manager Maurizio Sarri may be stubborn in his methods of trying to influence an attacking style of football at Stamford Bridge and that is something fans may have to accept.
"But winning the Premier League is about who gets the most points and there's different ways of getting points".
Though Sarriball at its peak is wonderful to watch, winning the league title with such a demanding style is always going to be hard, something he found at Napoli.