The Gunners were seconds away from being knocked off top spot at the Emirates Stadium when Nicklas Bendtner cancelled out an early Philippe Senderos own-goal to secure a 1-1 home draw against Aston Villa. Defeat would have left Arsenal's morale in tatters. Arsene Wenger believes his players were still suffering from a "hangover" caused by seeing their team-mate Eduardo suffer a sickening broken leg against Birmingham seven days previously and being knocked from top spot would have been one blow too many.
United, who would have gone top on goal difference had Arsenal lost, maintained the pressure on the leaders with a 3-0 win away to Fulham.
Chelsea, now seven points behind Arsenal with a game in hand, bounced back from last weekend's League Cup defeat with a 4-0 win away to West Ham.
The Blues played more than half the game with 10 men after Frank Lampard was sent-off against his old club after opening the scoring.
It was a different story for League Cup winners Tottenham as Birmingham City pulled clear of the relegation zone with a 4-1 win at St Andrews.
Third-bottom Reading ended a run of eight defeats with a 1-0 victory away to Middlesbrough thanks to James Harper's last-minute goal.
Sunderland, still without an away league win this season, missed a chance to pull clear of the bottom three after they were held to a goalless draw at basement club Derby County.
Newcastle were still left searching for their first win since the return of manager Kevin Keegan as Blackburn Rovers won 1-0 at St James' Park.
The home side squandered several chances before Rovers's Matt Derbyshire scored in the last minute.
Michael Owen might have had a hat-trick and afterwards Keegan, himself a former Liverpool, Newcastle and England striker, said: "Michael came straight into the dressing room, put his hands up and said, 'sorry guys, I should have scored'.
"But he won't go hiding, that's for sure. He puts himself up there, gets himself into positions and on another day he could have had a hat-trick.
"But today (Saturday), it wasn't to be. He is a top-quality player and a great finisher, but today, he put his hands up and said he should have scored a few goals.
Manchester City's hopes of European football next season suffered a setback when they were held to a goalless draw at home to strugglers Wigan in Saturday's late kick-off.
United manager Sir Alex Ferguson, who rested Wayne Rooney, Cristiano Ronaldo and Nemanja Vidic ahead of next week's Champions League clash against Lyon, said it had been great to give such key players a break.
"We did the job well. The pleasing thing was I was able to use my squad.
"We've got a massive game on Tuesday and resting Rooney and Ronaldo, it was vital for us to do that."
United took the lead at Craven Cottage when Owen Hargreaves scored his first goal for the club from a free-kick.
Then, just before half-time, South Korea international Park Ji-Sung doubled United's lead with a header from a Paul Scholes cross. An own-goal from second-bottom Fulham's Simon Davies made it 3-0 in the 72nd minute.
"Goal difference can make a big difference but the see-saw way it's been going in the last few weeks, it looks as if it is going to be a fantastic run-in," Ferguson said.
Arsenal fell behind when Swiss defender Senderos turned Gabriel Agbonlahor's cross into his own net.
Villa then defended impressively despite seeing Curtis Davies go off with an Achilles tendon injury that ended the centre-back's season before Bendtner stole in from close range late on to secure a precious point for the Gunners.
"We were dominated physically and technically in the first half," said Arsenal manager Arsene Wenger.
"But we battled to the last second to get a point. That point can have a vital importance for the rest of the season."
In the London derby at Upton Park, Chelsea scored three goals in the space of five minutes
Lampard started the spree with a 17th minute penalty after Anton Ferdinand fouled Salomon Kalou on the edge of the box.
Minutes later Joe Cole, another Hammers' old boy, made it 2-0 with a powerful shot. Germany midfielder Michael Ballack's well-struck half-volley made it 3-0.
Chelsea were reduced to 10 men in the 36th minute when Lampard was sent-off for a push on Luis Boa Morte.
However, that didn't stop Chelsea adding a fourth when former Arsenal full-back Ashley Cole scored his first goal for the club in the 64th minute.
At St Andrew's, Birmingham went ahead in the seventh minute when Mikael Forssell headed in a cross from James McFadden.
Sebastian Larsson's 55th minute free-kick made it 2-0 before Forssell completed his first club hat-trick. Jermaine Jenas's late goal was little consolation for Spurs.
Sunday sees attention focused on the race for Champions League qualification with fourth-placed Everton at home to Portsmouth while Liverpool, three points behind their city rivals, are away to Bolton Wanderers.