Teenager Julio Enciso scored a stunning winner as Brighton came from behind to beat Chelsea in the Premier League in Frank Lampard’s first home match since being reappointed Blues manager.
Paraguayan forward Enciso, 19, blasted into the top corner from 35 yards to help Brighton continue their European qualification push.
Substitute Danny Welbeck had levelled at Stamford Bridge after Conor Gallagher’s deflected strike gave Chelsea a fortunate lead.
Brighton remain seventh in the table and Chelsea 11th.
Enciso became the latest Brighton youngster to the hit the headlines as their shrewd deals in the transfer window continue to aid their drive up the league table.
He joined for a reported £9.5m from Paraguayan club Libertad Asuncion in the summer and has slowly been bedded into the side.
He earlier hit a post from a tight angle just after the restart with Welbeck unable to prod home the rebound.
Brighton’s controversial loss to Tottenham last Saturday ended their seven-match unbeaten run, but they dominated in west London even after conceding the opener.
Teenager Evan Ferguson struck the crossbar in the eighth minute, while Kaoru Mitoma forced a brilliant low save from Chelsea keeper Kepa Arrizabalaga midway through the first half.
Worryingly for Brighton, the in-form Ferguson landed awkwardly on an ankle after his header was tipped over the bar by Kepa.
He was replaced by Welbeck in the 39th minute and three minutes later the former Manchester United and Arsenal striker deservedly headed Pascal Gross’ deep cross in off the post.
Victory lifted Brighton to within a point of sixth-placed Aston Villa, having played two games fewer.
They face United in the FA Cup semi-finals at Wembley on 23 April.
Chelsea’s opener ended a run of four games without a goal.
It was a fortunate strike too as Gallagher’s shot deflected wickedly off defender Lewis Dunk and wrong-footed Brighton keeper Robert Sanchez, back in the team as a replacement for the injured Jason Steele.
Chelsea made six changes from their Champions League first-leg quarter-final loss to Real Madrid on Wednesday and looked disjointed throughout.
Their best chance came at the end of the first half, a Christian Pulisic header from close range striking the outside of the post.
Sanchez did well to keep out Reece James’ cross and then Mykhailo Mudryk’s follow-up early in the second half with the scores level.
Chelsea, who had never lost a home match to Brighton, find themselves 17 points off the top four, closer to the relegation zone than the Champions League spots.
They face Real in the second leg on Tuesday.