Christian Pulisic scored in the 90th minute to give Chelsea a 1-0 win over 10-man West Ham United.
Lukasz Fabianski thought he had earned West Ham a point after he had saved Jorginho's 87th-minute penalty, awarded for a foul on Romelu Lukaku by Craig Dawson, who received a straight red card for the denial of a clear and obvious goalscoring opportunity.
But substitute Pulisic met Marcos Alonso's low cross and found the bottom corner with Chelsea's 24th shot of the match to spare his side a third consecutive home match without a win.
It takes Chelsea to 65 points, five more than fourth-placed Arsenal with a match in hand.
West Ham, who started with Declan Rice, Jarrod Bowen and Michail Antonio on the bench, stay seventh on 52 points, eight off the top four with only four matches left.
See: Chelsea report | West Ham report
Next fixtures
Chelsea: 28 Apr v Man Utd (A)
West Ham: 1 May v Arsenal (H)
Match officials
Referee: Michael Oliver. Assistants: Stuart Burt, Simon Bennett. Fourth official: Peter Bankes. VAR: Paul Tierney. Assistant VAR: Simon Long.
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