Wilfred Ndidi's late equaliser rescued a point for Leicester against a West Ham side who battled valiantly with 10 men following a red card for captain Mark Noble.
Fabian Balbuena's first West Ham goal looked like it might be enough for victory when he scored after half an hour. Eight minutes later Noble was sent off for a challenge on Ndidi.
Leicester laid siege to the West Ham goal thereafter and finally made the breakthrough after 89 minutes with Ndidi's deflected strike making it 1-1.
Ndidi's effort rescued Leicester from a third straight Premier League loss, a defeat which would have been scrutinised further following Claude Puel's decision to drop Jamie Vardy.
The striker touched the ball just 11 times during the defeat to Arsenal on Monday and left the field of play five minutes before the final whistle at the Emirates Stadium because of a stomach problem. The issue also caused him to miss a training session this week.
Vardy resumed training on Thursday and declared himself "back to full strength" on Instagram a day later. However, Puel decided to leave out his star striker and revert to a 4-2-3-1 formation with Kelechi Iheanacho leading the line in attack.
It looked like a good decision when, with only two minutes on the clock, Iheanacho swept in a cross from Marc Albrighton. But the offside flag was up.
That was about as good as it got for Leicester in the first half as West Ham, who started the game tardily, improved and took control.
A lovely piece of skill by Felipe Anderson saw the Brazilian bring the ball down, glide past a couple of defenders and work Kasper Schmeichel with a fierce shot from the corner of the box.
Robert Snodgrass flashed a couple of efforts wide and it was no surprise when West Ham went ahead.
Anderson chipped the ball to the back post from a Snodgrass free-kick and Declan Rice headed it back across the penalty area where Balbuena saw his diving header hit the inside of a post before getting up to fire the rebound into an empty net from close range.
The complexion of the match changed with Noble's red card. The West Ham captain slid in on Ndidi, catching the Leicester midfielder on the shin. Referee Michael Oliver quickly pulled out his red card.
Despite the obvious surprise of Noble and his manager Manuel Pellegrini, the Northumberland official made the right decision. The challenge was late, high and dangerous.
Leicester almost took immediate advantage of their numerical advantage by equalising just before half-time but Vicente Iborra's diving header was brilliantly saved by Lukasz Fabianski.
With Leicester chasing the game, Puel introduced Vardy for the start of the second half, with Rachid Ghezzal making way, and the striker flicked a header wide.
West Ham were up against it with 10 men and Leicester, who had a couple of penalty appeals turned down, were starting to create openings regularly.
Fabianski made a fine double save to deny Albrighton just after the hour mark before Vardy glanced another header over the crossbar. Harry Maguire then saw a header clip the top of the bar after 67 minutes.
West Ham should have made sure of all three points eight minutes from time but substitute Angelo Ogbonna was unable to turn a free header on target.
Ndidi made them pay when his long-range shot took a huge deflection off Balbuena and spun the ball into the top corner of the net.
The match ended on a sour note with Leicester's Daniel Amartey being carried from the field on a stretcher needing oxygen after appearing to get his studs caught in the turf.