Pep Guardiola fell to a fourth successive defeat for the first time as Manchester City boss as Brighton came from behind to beat the Premier League champions.
It is the first time since 2006 that City have lost four in a row.
Manchester City looked on course to end their disappointing sequence when Erling Haaland capped an impressive opening at Amex Stadium in the 23rd minute, scoring at the second attempt from Mateo Kovacic’s pass.
Brighton, however, held their nerve, taking complete control after the break – and it was only their poor finishing that prevented them drawing level before substitute Joao Pedro pounced in a scramble 12 minutes from time.
City, who had looked increasingly vulnerable, were on the rack and Brighton took a deserved lead when Matt O’Riley, who has been out injured since his debut following a move from Celtic, burst through an exposed defence to beat keeper Ederson five minutes later.
Brighton earned the reward after passing up a number of chances, with Jack Hinshelwood heading straight at Ederson from point-blank range and Georginio Rutter also missing a golden opportunity before City crumbled under the constant pressure.