Chelsea's new loan-signing, Joao Felix, endured an agonizing debut when he was sent off in a 2-1 Premier League loss to crosstown rivals Fulham on Thursday, intensifying the scrutiny on embattled manager Graham Potter.
The Portugal forward, having just completed a loan move from Atletico Madrid, looked spry one day prior, but his performance was cut short in the 58th minute after being shown a straight red card for a reckless tackle on Fulham defender Kenny Tete when the score was 1-1.
Fulham made the most of the man advantage when Brazilian forward Carlos Vinicius, standing in for the club's suspended top scorer Aleksandar Mitrovic, put the hosts back in front in the 73rd minute with a clever header.
Former Chelsea winger Willian had put Marco Silva's side in front in the first half with a deflected shot but Potter's team leveled early in the second half through a scrappy goal from close range by defender Kalidou Koulibaly.
Kai Havertz had a late chance to equalize with a stinging effort but Fulham goalkeeper Bernd Leno was equal to it and Marco Silva's side held on to record their first league victory over Chelsea in 17 years.
The win lifted Fulham above Liverpool and up to sixth in the Premier League standings with 31 points after 19 games.
Chelsea, who fell to their eighth league defeat this season and third consecutive loss in all competitions, are 10th in the table on 25 points from 18 matches.
Manchester City had humbled Potter's side 4-0 in the FA Cup on Sunday but made a positive start at Craven Cottage, with Felix looking lively. He cut through Fulham's left-hand side to tee up Lewis Hall in the area but Leno saved the shot.
Felix had two attempts on goal but Fulham went ahead with the help of two defensive mishaps from Chelsea, Hall giving away possession and Trevor Chalobah deflecting Willian's shot into the net.
Chelsea showed character to quickly respond after the break, Koulibaly pouncing on the rebound after Leno had turned away a shot from Mason Mount.
They lost midfielder Denis Zakaria to injury, however, and Felix to a red card, the 23-year-old wildly lunging at Tete after losing the ball.