In his first appearance for nearly 10 months, Danny Welbeck struck in the fourth minute of injury time to give Arsenal a priceless 2-1 victory over Leicester City and cut the gap to their opponents at the top of the Premier League standings to just two points.

Despite losing Danny Simpson to two yellow cards at the start of the second half and Theo Walcott equalizing Jamie Vardy’s first-half penalty soon after, Leicester had appeared set to hang on and crucially retain their five-point advantage at the Premier League summit. But Welbeck, who has been forced to watch on from the sidelines for so long because of a knee injury, made a fairytale return off the bench, heading home Mesut Ozil’s free-kick with what was almost the last action of the game.

And with it he has blown this most unpredictable of Premier League title races wide open once more. As well as Arsenal closing the gap, Tottenham and Manchester City will have the chance to do likewise when they clash at the Etihad Stadium in Sunday’s other blockbuster matchup.

For Leicester it was cruel blow after what appeared would be yet another huge test successfully negotiated. Vardy had put them in front right before halftime, when taking the opportunity to go down under the outstretched leg of Nacho Monreal in the box, with the referee giving the benefit of the doubt to the Leicester striker. And the Premier League’s top scorer emphatically increased his season’s tally to 19 from the spot.

But their task of maintaining that advantage and securing back-to-back wins at Manchester City and Arsenal was dealt a major blow with two yellow cards in five minutes for right-back Simpson. Even Walcott’s equalizer following an exquisite cushioned header from Olivier Giroud with 20 minutes remaining was far from disastrous. A draw would undoubtedly have been far more palatable to Leicester in allowing them to maintain their five-point advantage over the hosts.

Yet in the most agonizing of circumstances it was not to be. And Claudio Ranieri will doubtless be left with a deep sense of frustration that two rash challenged from his players have proved so costly. After Simpson’s blatant and unnecessary holding back of Giroud’s arm to see red, substitute Marcin Wasilewski committed a needless foul in his own third of the pitch as injury time was about to tick to its conclusion. From the resulting free-kick, Ozil chipped it into the danger zone and substitute Welbeck got free to head home.

Still, Arsenal will feel they fully deserve the three points. Predictably dominating possession throughout, Arsenal had two penalty appeals of their own turned away in the first half, although on both occasions it was the right decision. Arsenal’s complaints were even more vociferous at the penalty awarded against then, even if Monreal had enabled the referee to make a decision by his clumsy challenge.

But iIt was all one-way traffic following Simpson’s dismissal, and indeed Leicester should have been reduced to nine men following Danny Drinkwater’s ugly, high tackle on Aaron Ramsey. With the one-man advantage, Arsenal created chances aplenty, both before and especially after Walcott’s leveler. Ramsey scuffed two wide of the post, Per Mertesacker headed an even better one wide and Kasper Schmeichel saved superbly from Giroud.

The fact that Leicester’s resistance broke at the very last provides arguably the biggest challenge yet of their ability to keep their heads in the most unlikely of title challenges. For Arsenal, after a rocky run of form, this was the kind of victory that could spark a run to their first title in 12 years.