The league leader's hopes of celebrating its first ever English Premier League title were put on hold Sunday after a 1-1 draw with Manchester United.
The Foxes, who at the start of this season were ranked as 5000-1 outsiders to win the league, needed victory at Old Trafford to secure the title.
But United started the match determined to spoil the party, playing with verve and freedom and looking nothing like the side that has appeared shackled in attack so often this season.
The 20-time champion quickly deflated the traveling Leicester fans with a goal inside 10 minutes.
Antonio Valencia stood up a cross that evaded everyone in the penalty area, before Anthony Martial ghosted in at the far post and swept the ball past Kasper Schmeichel.
Leicester, conversely, looked edgy and nervous and had Schmeichel -- son of legendary United goalkeeper Peter -- to thank for not going two goals down after he pulled off a brilliant save low to his right.
Sunday was the first time that the Leicester keeper had played at Old Trafford, where his father won five Premier League titles during his spell as a United player.
However, a spirited Leicester team haven't come this far -- the draw put them eight points ahead of second place Tottenham Hotspur -- for nothing.
Nine minutes after Martial put United ahead, Leicester captain Wes Morgan got his head onto Danny Drinkwater's free-kick to divert the ball past a helpless David de Gea.
With tensions rising, United's Belgian midfielder Marouane Fellaini was lucky to escape a red card after appearing to land an elbow on Robert Huth's throat.
If referee Michael Oliver failed to see the incident, Fellaini potentially faces a retrospective ban.
Leicester had loud appeals for a penalty turned down soon after the equalizer. Riyad Mahrez pulled out one of his trademark feints, completely deceiving Marcos Rojo who clumsily brought down the Algerian, but Oliver was unmoved.
The hosts achieved a season-high 70% possession in the game and limited Leicester to chances from set pieces.
Leicester striker Leonardo Ulloa was unfortunate not to get a heavier touch on Morgan's knock-down and the ball popped up into De Gea's outstretched arms.
"The performance was good after the first 15 minutes," Claudio Ranieri told Sky Sports after the game.
"Before our goal we were a little, little scared. United started very, very well and as big, big teams move the ball very well, it was very difficult for us to restart and make something good.
"I was worried but we have a very good heart and I said 'OK, sooner or later we react.' After their goal we had to react immediately and, fortunately with the first free kick, we scored.
"After our goal I think we played better, there were good chances for us and I think the draw is a right result."
Louis van Gaal's men began to pile on the pressure in the closing stages and felt aggrieved not to have been awarded a penalty.
Drinkwater clipped Memphis Depay's heels down the right, but referee Oliver deemed the foul outside the box and subsequently sent the Leicester midfielder off for a second yellow card.
The Foxes' vociferous fans were a constant source of noise in their corner of Old Trafford, willing the team to score the goal that would see them crowned champion.
But it was United which came the closest to winning the match after a tackle from Robert Huth inadvertently played the ball into Wayne Rooney's path, but Schmeichel was out quickly to smother the chance -- just one of a number of key saves the Leicester keeper made.
Leicester will now wait will bated breath for the outcome of Tottenham's match against Chelsea Monday.
If Spurs fail to beat its opponent, Leicester will be crowned champions.
But Ranieri won't be watching.
"I would like to watch the match but I think I am on a flight back from Italy," the Italian said with a wry smile. "So it will be difficult to watch.
"Maybe when I land I will find out the result."
Meanwhile, the draw for United diminished their chances of qualifying for next season's Champions League, with Van Gaal's team now four points behind fourth-place Manchester City.