Liam Rosenior's side trailed to first-half goals from Jarrod Bowen and Crysencio Summerville at Stamford Bridge.

But Chelsea ignored the half-time jeers from their angry fans, staging a brilliant revival after the break.

Joao Pedro reduced the deficit before Marc Cucurella headed the equaliser.

For the first time in the Premier League era, Chelsea came from two down at half-time to win thanks to their captain as Fernandez netted in stoppage-time.

West Ham's Jean-Clair Todibo was sent off for violent conduct after tempers boiled over in the final seconds.

In what Rosenior had labelled Chelsea's "biggest match of the season", the Blues showed their character in memorable fashion.

They climbed to fourth in the Premier League as Rosenior became only the fourth English manager to win his first three Premier League games after Bobby Gould, Sam Allardyce and Craig Shakespeare.

Rosenior has overseen six wins from seven games in all competitions since arriving from Strasbourg to replace Enzo Maresca.

The highlight of Rosenior's impressive start had come on Wednesday when the Blues fought back from 2-1 down to beat Napoli 3-2 in Italy, securing a place in the Champions League last 16.

But this was arguably even more eye-catching than that success, given how Rosenior turned the tide after Chelsea's wretched first half.

Rosenior will bid to work another miracle on Tuesday when Chelsea look to overturn a 3-2 deficit in the League Cup semi-final second leg at Premier League leaders Arsenal.

- From boos to bedlam -

He made seven changes after the victory in Naples, with Cole Palmer back in the starting line-up after starring from the bench in midweek.

Chelsea looked out of sync following the reshuffle and West Ham took advantage to go ahead in the seventh minute.

Bowen wriggled into space on the edge of the penalty area before curling in a cross that eluded the out-stretched boot of West Ham striker Pablo and caught Chelsea keeper Robert Sanchez flat-footed as it drifted into the far corner.

Rosenior suffered another blow when winger Jamie Gittens limped off injured after a challenge with Summerville.

Summerville inflicted more pain on Chelsea in the 36th minute.

In a flowing move from West Ham as Bowen picked out Aaron Wan-Bissaka and his cross was perfectly weighted for Summerville to thump a superb finish past Sanchez from 12 yards.

Alejandro Garnacho's dismal display drew the ire of angry Chelsea fans and the Argentine winger was put out of his misery as Rosenior took him off at half-time.

Rosenior also removed Benoit Badiashile and Jorrel Hato, but Sanchez had to save a fierce blast from Mateus Fernandes  after the restart.

Sanchez saved again to repel Bowen's snap-shot, yet just as Chelsea looked down and out, Rosenior's changes finally paid dividends.

Wesley Fofana's buccaneering run climaxed with a precise cross towards Joao Pedro, who rose highest to head past Alphonse Areola from close-range.

The Brazilian's fifth goal in his last five games was followed by Chelsea's 70th minute leveller.

Malo Gusto nodded Enzo Fernandez's cross to Liam Delap for a chance that bounced down off the bar towards Cucurella, whose diving header beat Areola from close-range.

Chelsea were rampant and Fernandez bagged the winner two minutes into stoppage-time.

Joao Pedro pulled his pass across goal and Fernandez thumped past Areola to celebrate his 150th Chelsea appearance in memorable fashion.

Todibo couldn't handle West Ham's collapse and he saw red after grabbing Joao Pedro around the throat.