Chelsea s Moroccan midfielder Hakim Ziyech celebrates after scoring their second goal during the English Premier League football match between Watford and Chelsea at Vicarage Road Stadium in Watford (AFP)
Substitute Hakim Ziyech grabbed the winner for the leaders in the 72nd minute, converting a cross from Mason Mount _ the England midfielder who had put Chelsea in front in the 29th.
By then, the teams had been taken off by the referee because of the medical emergency in the stands that happened after about 13 minutes. The incident happened on the side of the field where Chelsea left back Marcos Alonso was stationed and he appeared to alert the referee and the medical staff on the touchline.
The spectator was stabilized and taken away on a stretcher to applause from the crowd.
Emmanuel Dennis equalized for Watford in the 43rd after Ruben Loftus-Cheek _ one of a number of fringe players handed a start by Chelsea manager Thomas Tuchel _ was dispossessed in the center circle by Moussa Sissoko, who drove forward and set up his teammate to score.
Chelsea remained a point ahead of Manchester City and two clear of Liverpool on a night when all three teams won.
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