Leicester City's Premier League title dream moved closer to reality after a Wednesday wipe-out brought defeats for their nearest challengers Tottenham Hotspur, Arsenal and Mancheter City.
Tottenham were primed to take advantage of Leicester's 2-2 home draw with West Bromwich Albion on Tuesday and would have gone top on goal difference with victory at West Ham
United but they went down 1-0 to end a six-match winning run.
Michail Antonio's early headed goal proved decisive at Upton Park and if Leicester fans thought that was good their night got even better as third-placed Arsenal slumped 2-1 at home to Swansea City and fourth-placed City were thrashed 3-0 at Liverpool, three days after beating them in the League Cup final.
With 10 matches remaining, Leicester have 57 points, Tottenham 54, Arsenal 51 and City, who have a game in hand, 47, ahead of
Manchester
United
only on goal difference after Juan Mata's late strike earned them a 1-0 win over Watford.
West Ham, on 46 points, are also in the mix for Champions League qualification after putting the brakes on Tottenham's title charge in a typically tense derby in east London.
Antonio struck the game's only goal in the seventh minute, heading in Dimitri Payet's corner, and West Ham could have been further ahead before Tottenham improved in the second half.
Harry Kane wasted Tottenham's best chance, scuffing a close-range rebound after West Ham keeper Adrian saved a low 25-metre drive from Toby Alderweireld.
"We need to be positive and it is important to be ready for Saturday," Tottenham manager Maurico Pochettino, whose side host Arsenal on Saturday, told the BBC.
"When you lose you can blame it on the players being tired or whatever, the reality is that it was just a bad night."
Arsenal were hoping to bounce back from Sunday's defeat at
Manchester
United
and Joel Campbell firing them ahead but goals from Wayne Routledge and Ashley Williams gave Swansea three vital points in their bid to move away from trouble.
Manager Arsene Wenger said his side were unlucky but Arsenal's fans made their feelings clear, booing the side off after a dismal second-half display.
"They had two shots on target and scored two goals," said Wenger, who added that keeper Petr Cech had picked up an injury that will rule him out against Tottenham.
"We need to bounce back very quickly now."
Manchester
City's third consecutive league defeat left them looking over their shoulders.
Adam Lallana, who missed one of Liverpool's penalties in Sunday's Wembley shootout, and James Milner scored before halftime and Roberto Firmino sealed the points after the break.
With City's league form disintegrating, Louis van Gaal's
United
side are now back in the frame for a top-four spot, even if they were poor against Watford before Mata's winner.
The Spaniard's sublime 83rd-minute free kick was harsh on Watford who wasted a flurry of chances at Old Trafford.
At the other end of the table, Newcastle
United's plight worsened as a 1-0 defeat at Stoke City left them second from bottom with 24 points, the same total as Norwich City and Sunderland who are directly above them.