Arsenal lost more ground in the race for the top four as Youri Tielemans and Jamie Vardy found the net after Ainsley Maitland-Niles was shown a red card during the first half.
Maitland-Niles made an early exit after being shown two yellow cards with the Foxes going on to make their numerical advantage count after the break.
Tielemans broke the deadlock with a well-placed header before Vardy sealed the three points with two late finishes.
Defeats to Crystal Palace and Wolves in the past week had already damaged the Gunners’ hopes of securing a top-four spot but their latest reverse against the Foxes now means they could end the day four points shy of the Champions League qualification places, if Chelsea overcome Manchester United.
