London: Danny Welbeck, making his first appearance of the season as a late substitute, headed a stoppage-time winner as Arsenal boosted their hopes of winning the Premier League title with a 2-1 home win over league leaders Leicester City.
Meanwhile, title rivals Tottenham beat Manchester City 2-1 away at the Etihad Stadium. At Villa Park, Liverpool crushed Aston Villa 6-0, pushing the league strugglers even closer to relegation.
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A goal from Danny Wellbeck in injury time gave Arsenal a win over Leicester while Tottenham stunned Manchester City as the title race was set alight.
Welbeck, who had not played since last April after a series of injuries, came on after 83 minutes and scored in the fifth minute of stoppage time when he glanced home a Mesut Ozil free kick to secure the victory.
The win lifted Arsenal to 51 points, two behind Leicester, who played most of the second half with 10 men after defender Danny Simpson was sent off in the 54th minute.
"It was a pivotal moment today because the mathematics meant it could be eight points or it could be two points. That is a great change," Arsenal manager Arsene Wenger told Sky Sports.
"There's a long way to go, we play a lot of big teams. But we had a bad spell where we couldn't win for four games and have now won two on the bounce. We have come out of that bad spell and still have a good chance."
Leicester, seeking a first ever top-flight title, had not beaten Arsenal in their last 18 league matches but after surviving some early pressure, took the lead in the 45th minute when Jamie Vardy scored with a penalty after referee Martin Atkinson ruled that he had been fouled by Nacho Monreal.
Vardy smashed home his 19th league goal of the season giving Petr Cech no chance of saving but the balance of power swung heavily in Arsenal's favour after Simpson's dismissal.
He was booked twice in five minutes, the second time for a clumsy challenge on Olivier Giroud and most of the second half was played out in Leicester's half of the field.
Arsenal's dominance paid off after 70 minutes when substitute Theo Walcott equalised from close range after Giroud's header found him in space.
However they could find no way past goalkeeper Kasper Schmeichel – who made a series of excellent stops – until the dying seconds when Welbeck, rose above the defence to seal a hugely significant victory.
Leicester manager Claudio Ranieri told Sky: "We are still top of the table – we must carry on and smile. We lost to our opponents – we must say well done."
In Manchester, Christian Eriksen celebrated his 24th birthday with the winning goal for Tottenham when they beat Manchester City to stay second in the Premier League table.
Spurs broke the deadlock in the 53rd minute after referee Mark Clattenburg ruled that City's Raheem Sterling had handled in the area even though he turned his back as Danny Rose crossed and the ball hardly seemed to hit his arm.
But that did not worry Kane who fired his spot kick down the centre of the goal and past his England team mate Joe Hart into the net.
Yaya Toure almost equalised for the home side when he hit the bar with a 57th minute free kick, but they were soon level when Kelechi Iheanacho swept a cross from Gael Clichy into the roof of the Spurs net.
Eriksen though gave Spurs all three points when he scored in the 83rd minute after a surging run from Erik Lamela.
In Birmingham, Liverpool crushed Aston Villa, leading to a mass exodus of home fans long before the final whistle at Villa Park.
Liverpool went ahead when Daniel Sturridge, who has been injured for most of the season, headed in after 16 minutes before former Villa winger James Milner doubled their lead with an inswinging free kick eight minutes later.
Villa collapsed midway through the second half conceding four goals in 13 minutes with Emre Can starting the blitz with a 25-metre shot that beat keeper Mark Bunn after 57 minutes.
Divock Origi burst through to make it 4-0 a minute after coming on as a substitute before England defender Nathaniel Clyne made it 5-0 with a tap-in and Kolo Toure headed a sixth in the 70th.
The victory ended Liverpool's run of five matches without a win in all competitions.