Ollie Watkins emerged from the bench to spearhead a superb Aston Villa revival as they came from behind to confirm their Premier League title credentials at Chelsea with an 11th successive win in all competitions.
Chelsea deservedly led after 37 minutes when striker Joao Pedro got a vital touch in a goalmouth scramble as Villa tried to clear Reece James' corner.
Villa, seeking to equal a club record set in both September 1897 and March 1914, had been second best until manager Unai Emery made a triple substitution just before the hour, sending on Watkins, Amadou Onana and Jadon Sancho for Emiliano Buendia, John McGinn and Donyell Malen.
Emery's golden touch worked inside four minutes as Watkins raced on to Morgan Rogers' pass, Chelsea keeper Robert Sanchez saving at his feet only to see the rebound bounce in off the striker.
Villa were transformed, and it needed crucial saves by Sanchez from Ian Maatsen and Boubacar Kamara to keep Chelsea, who had dominated for so long, on level terms.
However, Chelsea were unable to keep a rampant Villa at bay, Watkins the scorer once more as he rose to power Youri Tielemans' corner past Sanchez.
Villa's win keeps them just three points behind Premier League leaders Arsenal.
BBC