Dean Hammond snatched a vital point for Brighton for their fight for Championship survival with a last-minute equaliser.
The young midfielder headed his second goal of the game from a Richard Carpenter cross to pinch a third draw on the trot for the struggling Seagulls.
It was a blow to West Ham's promotion charge, although a point was still enough to move them into the play-off zone above Reading.
Brighton remain in a relegation place with two games to go, but are now only behind Crewe on goal difference.
West Ham took an eight minute lead from their first attack. Marlon Harewood challenged in the air with Guy Butters and the ball bounced loose for Nigel Reo-Coker to bravely nod in from close range.
Brighton manager Mark McGhee made a substitution in the 51st minute, bringing on Gary Hart for Adam El-Abd. The change paid off immediately, Hart providing the cross two minutes later from which Hammond headed the equaliser.
West Ham were back in front within two minutes, when Butters miscued a header from Chris Powell's long free-kick and Harewood tucked away his 19th goal of the season.
McGhee threw caution to the wind, bringing on Jake Robinson as part of a four-man attack.
Harewood missed a chance to seal the points for West Ham with a scissors kick over the bar from five yards from a Shaun Newton cross that proved costly for the Hammers as their defence failed to clear a Carpenter corner.
The ball went back to the Brighton midfielder and his cross was headed in by Hammond for his third goal in two games.
Brighton, without a win nine matches, now have the opportunity to boost their survival bid away to the relegated Rotherham.
The young midfielder headed his second goal of the game from a Richard Carpenter cross to pinch a third draw on the trot for the struggling Seagulls.
It was a blow to West Ham's promotion charge, although a point was still enough to move them into the play-off zone above Reading.
Brighton remain in a relegation place with two games to go, but are now only behind Crewe on goal difference.
West Ham took an eight minute lead from their first attack. Marlon Harewood challenged in the air with Guy Butters and the ball bounced loose for Nigel Reo-Coker to bravely nod in from close range.
Brighton manager Mark McGhee made a substitution in the 51st minute, bringing on Gary Hart for Adam El-Abd. The change paid off immediately, Hart providing the cross two minutes later from which Hammond headed the equaliser.
West Ham were back in front within two minutes, when Butters miscued a header from Chris Powell's long free-kick and Harewood tucked away his 19th goal of the season.
McGhee threw caution to the wind, bringing on Jake Robinson as part of a four-man attack.
Harewood missed a chance to seal the points for West Ham with a scissors kick over the bar from five yards from a Shaun Newton cross that proved costly for the Hammers as their defence failed to clear a Carpenter corner.
The ball went back to the Brighton midfielder and his cross was headed in by Hammond for his third goal in two games.
Brighton, without a win nine matches, now have the opportunity to boost their survival bid away to the relegated Rotherham.