Joao Felix was sent off on his Chelsea debut as his new side lost a west London derby at Fulham to increase the pressure on Blues boss Graham Potter.
Joao Felix, who only joined Chelsea on Wednesday in a £9.7m loan deal until the end of the season from Atletico Madrid, was shown a straight red card for a horrible lunge on defender Kenny Tete after 58 minutes.
It was 1-1 at the time, with Willian putting the hosts ahead against his former side in the first half, before Kalidou Koulibaly equalised early in the second.
But the 10 men of Chelsea could not hang on to a point as Carlos Vinicius headed in a 72nd-minute winner.