Conor Gallagher returned to Selhurst Park to haunt Crystal Palace with a stunning late winner to give Graham Potter a controversial first win as Chelsea boss.
Substitute Gallagher, who impressed on loan at Palace last season, curled home a superb right-footed effort to snatch victory for Chelsea with his first goal for the club.
Pierre-Emerick Aubameyang also scored his first Chelsea goal on his Premier League return after Odsonne Edouard had poked Palace into an early lead.
However, there was controversy surrounding Aubameyang's goal as it was set up by Thiago Silva, who Palace felt should have been sent off for a deliberate handball which denied Jordan Ayew a possible goalscoring opportunity.
Gallagher, whose impressive form for Palace last season earned him his England debut, was introduced by Potter in the 76th minute for Kai Havertz.
And with the game seemingly petering out for a draw, the 22-year-old midfielder nutmegged Jean-Philippe Mateta and sent a curling shot into Vicente Guaita's top corner.