Chelsea lost 1-0 to Aston Villa at Stamford Bridge on Sunday, while Brighton came from behind to beat Bournemouth 2-1.
Ollie Watkins scored the only goal of the game for Villa in the second half, while Chelsea had Malo Gusto sent off for a studs-up challenge on Lucas Digne.
The defeat leaves Chelsea in 14th place in the Premier League table, while Villa move up to sixth.
At the Amex Stadium, Bournemouth took the lead through Dominic Solanke, but Brighton equalised through an own goal by Milos Kerkez just before half-time.
Substitute Kaoru Mitoma scored twice in the second half to give Brighton their third consecutive Premier League victory.
The win lifts Brighton to third place in the table, while Bournemouth remain winless after six games.
