Chelsea's challenge for a place in next season's Champions League faltered in a toothless 1-0 defeat at Arsenal on Sunday as Manchester United continued their upward trend with a 3-0 win at Leicester.
Mikel Merino scored the only goal of a disappointing contest at the Emirates as Arsenal pulled clear in second place and to within 12 points of runaway leaders Liverpool.
Chelsea badly missed the presence of the absent Cole Palmer due to injury as they meekly surrendered to a damaging defeat for their hopes of a top-four finish.
The Blues remain in fourth for now but have five sides from fifth-placed Manchester City to Aston Villa in ninth within four points of Enzo Maresca's men.
Both managers are hoping to be stronger after the upcoming international break.
Bukayo Saka is nearing a return for Arsenal, while Maresca is confident of having Palmer, Nico Jackson and Noni Madueke back when they are next in action at home to Tottenham on 3 April.
"We did enough to deserve to win the game," said Arsenal boss Mikel Arteta. "Now we have the international break so let's take a chance to breathe and bring some players back hopefully."
Arsenal have struggled badly for goals since the loss of Kai Havertz to a season-ending injury forced midfielder Merino into a makeshift centre-forward role.
The Spanish international proved the match winner from a corner as he looped a header from Martin Odegaard's delivery inside the far post on 20 minutes.
Chelsea's Robert Sanchez made a brilliant stop to prevent Merino doubling Arsenal's lead with the best effort of the second half.
But the game petered out with little goalmouth action as a limp performance will do little to quieten the critics of Maresca's style of play among the Chelsea support.
LEICESTER SET UNWANTED RECORD
United extended their unbeaten run in open play to seven games with a comfortable victory at seemingly doomed Leicester.
Rasmus Hojlund ended a 21-game goal drought by firing United in front on 28 minutes.
Alejandro Garnacho was made to wait for his first goal since November as the Argentine was flagged offside early in the second half.
Garnacho, though, was not to be denied with a snap shot that Mads Hermansen should have kept out.
United have won all four meetings against Leicester this season, two of which the Foxes' current boss Ruud van Nistelrooy was in interim charge of the Red Devils.
But the Dutchman has not had the same impact at the King Power.
Leicester have lost 13 of their last 14 league games to fall nine points adrift of safety.
Van Nistelrooy's men also set an unwanted record of becoming the first Premier League side to go seven home games without scoring.
Bruno Fernandes unsurprisingly set the seal on United's win with a stunning strike from the edge of the box for his seventh goal in seven games.
Tottenham kept their season alive by reaching the Europa League quarterfinals with victory over AZ Alkmaar on Thursday, but suffered the latest in a series of European hangovers in a 2-0 defeat at Fulham.
Ange Postecoglou's side have won just three times in the 10 league matches that have followed a midweek European fixture.
"It's been a difficult campaign for sure," said Spurs captain Son Heung-min.
"But I feel we've lost too many games that we should have got stuff out of, and this was one of those games."
Victory for Fulham propels Marco Silva's men into the race for Champions League places as they climb to eighth, four points off the top four and three outside the top five.
A top-five finish will almost certainly secure a place in Europe's top club competition next season thanks to the strong performance of English sides in European competitions.
Fulham had to wait until 78 minutes to take the lead when Rodrigo Muniz steered home from Andreas Pereira's pass.
Ryan Sessegnon then curled in a brilliant second against his former club to secure victory late on.
Spurs slip down to 14th, now 10 points off the top half.