Fans booed the Italian's substitutions during the fifth-round match, and joined in when United supporters sang "you're getting sacked in the morning".

"This is Maurizio Sarri's last game at Chelsea. The Italian job is over for them," said BBC Radio 5 live pundit Sutton after the 2-0 home defeat.

"He's done."

Sutton, who played for Chelsea in 1999-2000, said: "He'll get the sack for numerous reasons - things he's said, that he can't motivate the players, his inability to be able to adapt and change.

"He won't survive tonight. Well he might until 9am tomorrow [Tuesday]."

Ander Herrera and Paul Pogba scored United's first-half goals as they reached the quarter-finals, where they will face Wolves.

Chelsea, who are sixth in the Premier League, meet Malmo in the Europa League last-32 first leg on Thursday, and Manchester City in Sunday's Carabao Cup final.

"Why risk him taking charge of a game against Manchester City?" said Sutton, speaking eight days after City beat Chelsea 6-0 in a Premier League game.

Former Napoli boss Sarri - who has never won a trophy as a manager - replaced fellow Italian Antonio Conte last summer.

He altered the team's tactics from a wing-back system to a 4-3-3, with several players struggling to adjust to the change.

Sarri has also been criticised for what are seen as predictable substitutions. Monday's game was the sixth time in 10 matches that one of Ross Barkley or Mateo Kovacic has been substituted on for the other in the second half, with Willian and Pedro involved together in another four changes in that time.

Blues fans called for teenage winger Callum Hudson-Odoi and chanted "you don't know what you're doing" at Sarri when Italian right-back Davide Zappacosta instead came on for the final eight minutes.

'I don't think they should sack him now'

Sarri told BBC Sport after the defeat that he was not worried about his position, and former Manchester United defender Phil Neville said he should be given more time.

"I don't think they should sack him now," Neville said on BBC One. "He plays good football, even if it is a little predictable.

"But Sarri is stubborn and stubbornness can get you the sack.

"Winning a trophy on Sunday might drag him out of trouble.

"He has brought in four players and needs another four or five and he has to keep Eden Hazard. He needs to bring in quicker players who can play his style of football."

'Sarri-ball is broken'

Chelsea owner Roman Abramovich has made 12 managerial changes since buying the club in 2003, and Sutton says he would "have to question the owner's ambition" if he does not sack Sarri now.

"Sarri-ball is broken," said Sutton of the Italian's tactics.

"Would the owner fancy getting into the top four with recent performances, with a manager who says he can't motivate his players and says he will let his star man go?

"The Chelsea owner will be thinking, 'Will we get top four? Can I go to the Manchester City game with confidence?' Absolutely not. Is he going to chuck all his eggs in the Europa League basket with a manager who can't motivate his players? No.

"History tells us the Chelsea owner doesn't mess about."

'Something needs to change'

BBC pundit Jimmy Floyd Hasselbaink, who scored 81 goals for Chelsea, said these are "worrying times" for his former club.

"They've got important matches coming up and they need to pick themselves up," he said. "Without the ball they showed no reaction, no hunger to get the ball back. It's all nice with the ball, but they didn't create.

"Chelsea are in trouble. Something needs to change. The balance in midfield is not right.

"Sarri sticks to his beliefs. That is the system he wants to play, fair enough, but something is not right in that midfield.

"Chelsea are not creating enough for the strikers."

'The team are not responding to anything he does'

Former Arsenal full-back Lee Dixon also thinks "something has to change".

He said: "If Sarri is reluctant to change the personnel or tactics, or maybe put some young players in, you have to say the owner will look at this and say: 'Where can we go from here?'

"The fans let the players and manager know how they were feeling. The night fizzled out. The tactics... we know what will happen from minute one to minute 90. Sometimes it works. When it doesn't work, they look awful.

"The midfield look terrible without the ball right now. The defence is shell-shocked. They're not scoring goals from midfield. When you're leaking goals and not scoring goals, your confidence is low and the tactics don't really change. There are no positives tonight apart from the work-rate of Hazard.

"Sarri has got some serious thinking to do. The team are not responding to anything he does."