Maurizio Sarri feels the heat as Chelsea fans turn against the Italian coach

As Chelsea laboured to yet another defeat with a 0-2 FA Cup fifth-round elimination by Manchester United on Tuesday, howls of frustration broke out from the home supporters tired of coach Maurizio Sarri's familiar tactics.

Chelsea's loss of form has been so steep since their early-season promise, that some supporters began to chant about their own coach facing being 'sacked in the morning' just seven months after the Italian arrived at Stamford Bridge.

Others resorted to expletives to voice their mounting disapproval of  'Sarri-ball,' as his style has been dubbed.

"I am worried about the results, not about the fans. Of course I can understand the fans because the result was not good," Sarri said.

The shortcomings of Sarri's Chelsea were once again laid bare, this time by a resurgent United who have won 11 times in 13 games under caretaker manager Ole Gunnar Solskjaer.

While Paul Pogba created the visitors' first goal for Ander Herrera and scored the second himself, with both coming from headers, Jorginho – the central midfielder Sarri brought with him to London from Napoli last year – struggled to leave a mark.

Pogba's midfield partner Herrera got himself on the scoresheet with a precise finish after a fine build-up, a stark contrast to Mateo Kovacic who was invisible for Chelsea.

Rare Threats

United's defence snuffed out the rare threats from Chelsea's Eden Hazard and Gonzalo Higuain, while the hosts – still smarting from a 0-6 Premier League humiliation by Manchester City a week earlier, looked brittle at the back whenever the powerful running of Marcus Rashford put them to the test.

But most alarming for Chelsea fans, is the lack of flexibility displayed by Sarri when under pressure to turn around his team's fortunes.

Loud boos rang out when he decided to make the familiar substitution of Kovacic by Ross Barkley and the discontent was louder still when Sarri, with Chelsea chasing a goal to get back into the game, opted to bring on fresh legs in defence as Davide Zappacosta replaced Cesar Azpilicueta.

Sarri said the solution lay in his players finding greater aggression and determination on the pitch.

"It's really very easy. If we are able to win three or four matches in a row it will be very easy," he said.

Chelsea have three important fixtures coming up, the second leg of their Europa League tie against Malmo of Sweden on Friday, the League Cup final versus Manchester City on Sunday and next Thursday's Premier League visit of Tottenham Hotspur. 

But Sarri, whose sixth-placed team are a point behind United in fourth, said he was not feeling the pressure even at a club which has seen a dozen managers come and go in the 15 years since it was bought by Russian oligarch Roman Abramovich. 

"I was really very worried when I was in league two in Italy. Not now," he said.