Having conceded a last-gasp equaliser at Manchester City last weekend, Arsenal looked determined to make a fast start against their newly-promoted visitors.
Bukayo Saka saw a low effort smartly saved by Mads Hermansen while Gabriel Martinelli blazed wastefully over the bar from inside the box.
The hosts’ pressure finally paid dividends in the 20th minute when Jurrien Timber’s inviting delivery was tucked into the bottom corner by Martinelli for his first goal of the season.
The one-way traffic showed no signs of slowing down as the first half progressed, with Hermansen reacting well to thwart Martinelli and Kai Havertz spurning a glorious chance from close range.
Not to be denied, the Gunners deservedly doubled their lead on the stroke of HT, as Martinelli’s intelligent cut-back was guided into the far corner by Trossard.
Determined to improve on a dreadful first-half showing, Leicester stunned the hosts within two minutes of the restart, with James Justin heading home from Facundo Buonanotte’s free-kick to halve the deficit.
Undeterred, Arsenal came close to immediately restoring their two-goal advantage, but Hermansen stood firm in the Foxes’ goal to deny Gabriel and Trossard in quick succession.
Grateful for those reprieves, Leicester remarkably found a leveller in the 63rd minute, as Justin met Wilfred Ndidi’s delivery with a sublime first-time volley to send the travelling support into raptures.
Having seen title rivals Man City drop points earlier in the day, Arsenal went in pursuit of a winner with time ticking into the final 20 minutes, however Hermansen continued to star for the visitors, saving brilliantly from Havertz and Trossard.
The Dane was finally beaten in the fourth minute of stoppage time though, as Trossard’s back-post effort was deflected over the line to secure a crucial three points for the Gunners in dramatic fashion.
Havertz added late gloss to the scoreline with a fortuitous close-range finish, as Arsenal moved level on points with Pep Guardiola’s side at the Premier League summit.
Flashscore Man of the Match: Mads Hermansen (Leicester City)
