Marco Silva's Fulham moved level on points with Chelsea following a 2-1 win at home.
The Blues begun with confidence, but a straight red card shown to defender Marc Cucurella threw a spanner in the works.
Fulham pressed the advantage, and had a goal ruled out for offside in the first half, before opening the scoring early in the second through Raul Jimenez.
Chelsea picked themselves up in the latter stages and found an equaliser through Liam Delap, but it proved fruitless as Harry Wilson added a second for the hosts with less than ten minutes on the clock.
It's a bitter end for interim coach Calum McFarlane, as well as a tricky situation for Liam Rosenior, who will take over permanently from Thursday.
His first test at the helm will be against Charlton Athletic in the FA Cup this weekend - whilst Fulham also face Championship opposition in the cup in Middlesborough.
Story of the Match
Fulham welcomed the Blues to Craven Cottage after a fiery 2-2 draw against reigning champions Liverpool. Harrison Reed was an unlikely goalscorer as he levelled things up deep in injury time - with a strong contender for goal of the season.
Marco Silva's side were unbeaten in their last five matches, but faced a Chelsea side that had emerged victorious from seven of their last ten meetings.
The two sides met earlier in the season - with former Blues head coach Enzo Maresca producing a 2-0 victory.
His successor Liam Rosenior would watch over this game: not from the dugout, but from the stands.
In a pre-match interview, he spoke highly of his new squad and their mentality surrounding a tumultuous period at the club - and had plenty of praise for interim coach Calum McFarlane, who oversaw his second and final match in charge before returning to his duties with the Under-21s.
The opening lacked many dangerous shots on target - Harry Wilson, who has been clinical for the Cottagers as of late, pounced on a first time shot in the Chelsea box, but Robert Sánchez was quick to react.
The Blues maintained possession and were intense in the press, committing several bodies forward, but lacked creativity and progressive passes to Liam Delap up front.
Cole Palmer had been starved of goal contributions, and was being kept under control by the left back Antonee Robinson, whilst Pedro Neto struggled to make an impact on the game on the opposite flank.
The home side had found early luck from open play, but Chelsea were threatening from set pieces, with two early corners nearly sneaking into the back of the net. The second was the closest - defender Tosin nearly found a breakthrough with a follow-up strike after Enzo Fernandez's initial delivery rattled off the crossbar.
Things soon came crashing down, however, as defender Marc Cucurella was shown a straight red for denying a goal scoring opportunity. Bernd Leno found Harry Wilson with a long pass following a corner, and the midfielder was dragged down just outside the box.
Tosin, Fernandez and Palmer were all booked for dissent in the aftermath, which highlighted the continued discipline issues of this young squad. Jorrel Hato was introduced in order to restore some defensive solidity, with Andrey Santos the unfortunate player to make way.
Fulham took full advantage of the chaos and volleyed several decent efforts at Chelsea's goal. They opted for more long balls and quick forward passes in an attempt to break past a vulnerable Blues defence.
They had also found lots of space in their opponents penalty box, and were carving out chances for their target man Raul Jimenez. Emile Smith Rowe had time to send in a cross from the left flank, but there was too much power on the delivery and it missed the mark.
Harry Wilson had been a constant menace in Fulham's attack, and had the ball in the back of the net just before half-time - but a VAR check caught Jimenez offside in the build-up. It was a fantastic passing move regardless by the hosts, and a massive wake-up call for the visitors, who had looked lifeless and disjointed since the red card.
There was a change of shape for Fulham in the second half as Marco Silva swapped defender for midfielder - Kevin brought on for the already booked Jorge Cuenca.
Chelsea struggled to get out of the blocks, and begun as they had ended the first 45 minutes. Jorrel Hato found space for a header from another dangerous corner, but the angle was a difficult one and it sailed over the bar.
At the other end, Fulham finally broke the deadlock through Raul Jiminez, who glanced a header into the bottom left corner following a brilliant delivery by Sander Berge.
Soon afterwards, substitute Kevin was given licence to drive towards the Chelsea box and released a powerful right-footed shot, which grazed the side netting.
Liam Delap had been positive in the striker spot - he featured up front in the reverse of this fixture earlier in the season, before picking up a hamstring injury which saw him sidelined for several months.
Having worked with Rosenior previously at Fulham, he will have been wanting to make an impression, and nearly got his side back on level terms after timing his run in behind.
With twenty minutes to go, he had his goal - his first in the Premier League - after pouncing on a rebound from a Pedro Neto corner. The Blues had begun to apply pressure at the other end and their hard work proved fruitful as they levelled the scores.
Chelsea surely had belief in a winning goal, and rang the changes, with Joao Pedro and Josh Acheampong both brought into the game, as well as Reece James.
Fulham continued to probe and looked to find Jimenez once again - the Mexican international arrived at the far post from a cross but could not find a way through a scrambling Sanchez, who made himself big to deflect the effort.
The home side kept up the pressure and eventually found their second goal through Harry Wilson, who flicked the ball away from Jorrel Hato and produced a brilliant strike which flew through the legs of Reece James and past the reaches of Sanchez.
It left very little time for the Blues to level things up once again, and capped off a frustrating evening for the visitors - who had failed to create many clear-cut chances.
With the advantage, Fulham were able to make their final few substitutes and see out the win, extending their unbeaten run to five games in the league.
Fulham's in-form midfielder was the standout star of the show, scoring his side's winning goal in fantastic fashion.
Wilson may have well scored in the first half after being released one on one following a corner - a move which resulted in a sending-off for Marc Cucurella, who dragged him to the ground just outside the penalty box.
It was a reflection of his quality during the game: always threatening just outside the danger area, using his awareness of the game to find space and create dangerous opportunities.