Leicester were knocked off top spot with a defeat by managerless Crystal Palace that ended their 100% home run in the Championship this season.
Damien Delaney fired home the opening goal from 12 yards before Peter Ramage headed in Yannick Bolasie's cross.
The Foxes created few chances as Palace made light of the departure of manager Dougie Freedman to Bolton to extend their unbeaten run to 10 and go fourth.
Andy King's stoppage-time header was only a consolation for the hosts.
The visitors, under the stewardship of caretaker boss Lennie Lawrence, could have gone ahead in the first minute but Bolasie spurned a chance from close range.
Julian Speroni - making his 250th league start in goal for the Eagles - had to be at his sharpest to save a David Nugent effort as the Foxes briefly threatened at the other end.
Palace took the lead after 23 minutes when Kaspar Schmeichel failed to deal with a Mile Jedinak corner and Delaney lashed home the loose ball.
Five minutes later, Ramage stole in unmarked to power home a header from six yards.
Leicester's performance improved slightly after the break and Jamie Vardy should have done better with a header that sailed over the bar.
But the goal did not arrive until the second minute of stoppage time when substitute Ben Marshall's cross was crisply headed past Speroni by King.
Palace's win moves them to within one point of second-placed Leicester.
Leicester manager Nigel Pearson: "Too many of our lads failed to find the form they have shown so far, but what we never did was to down tools. They're an honest bunch and they kept going.
"When you concede two goals in five or six minutes it makes a big contribution to any match. Today we didn't quite have the quality we needed to get back. We huffed and puffed without quite finding our feet.
"We have done exceptionally well so far this season but were beaten by a good side.
"We will now pick ourselves up for two tough away games at Watford and Bolton. I'm disappointed we've lost top spot, but I won't be dwelling on it for too long."
Crystal Palace caretaker boss Lennie Lawrence: "We knew exactly how difficult it would be at Leicester who will be in the top six at the end of the season without a shadow of a doubt. We had a game plan and it worked.
"We started boldly and scored two goals whereas at Barnsley we just got one. We knew they'd throw everything at us and they did but we defended resolutely, Julian Speroni made some saves and we rode a few moments of luck.
"Whoever takes charge will have a side that has every chance of maintaining a play-off challenge. They are so good as a unit, they could probably run themselves for a week or two.
"They have been absolutely spot on since Dougie left - if they weren't, you could never come to a place like this and win."
Live Text Commentary
Full Time The match has reached full-time.90:00 +3:17 Booking
Booking The referee shows Dean Moxey a yellow card for time wasting.90:00 +3:09 Substitution
Substitution Dean Moxey comes on in place of Wilfried Zaha.90:00 +1:22
Assist by Paul Konchesky.90:00 +1:22 Goal scored
Goal! - Andy King - Leicester 1 - 2 C Palace Andy King grabs a headed goal from inside the penalty box. Leicester 1-2 Crystal Palace.90:00 +1:14
The ball is crossed by Paul Konchesky,88:07 Substitution
Substitution Aaron Wilbraham comes on in place of Glenn Murray.87:26
Short corner worked by Yannick Bolasie.87:05
Wilfried Zaha takes a shot. Save by Kasper Schmeichel.86:14
Corner taken by Ben Marshall from the right by-line, clearance by Owen Garvan.79:16
The referee blows for offside against Glenn Murray. Kasper Schmeichel restarts play with the free kick.77:01
Paul Konchesky concedes a free kick for a foul on Joel Ward. Free kick taken by Julian Speroni.76:06 Substitution
Substitution Jeff Schlupp replaces Anthony Knockaert.74:41
Short corner taken by Anthony Knockaert.73:04
Wilfried Zaha takes the free kick.73:04 Booking
Booking Ritchie De Laet shown a yellow card.72:52
Unfair challenge on Yannick Bolasie by Ritchie De Laet results in a free kick.69:50
Matty James has an effort at goal from long range that misses to the right of the target.69:28
Unfair challenge on Zak Whitbread by Wilfried Zaha results in a free kick. Ben Marshall takes the direct free kick.68:48
Corner taken left-footed by Anthony Knockaert, clearance made by Damien Delaney.
Anthony Knockaert takes the outswinging corner, clearance made by Wilfried Zaha.65:29
Inswinging corner taken from the right by-line by Anthony Knockaert.61:42
Anthony Knockaert has a direct shot on goal from the free kick.61:42 Substitution
Substitution Ben Marshall replaces Danny Drinkwater.61:42
Damien Delaney gives away a free kick for an unfair challenge on David Nugent.60:48
Wilfried Zaha fouled by Paul Konchesky, the ref awards a free kick. Wilfried Zaha restarts play with the free kick.59:55
Inswinging corner taken by Owen Garvan, Danny Drinkwater makes a clearance.54:59
Jamie Vardy has a header from close range and clears the crossbar.54:14
Corner from the left by-line taken by Anthony Knockaert, Damien Delaney manages to make a clearance.52:19
Inswinging corner taken by Anthony Knockaert, clearance made by Owen Garvan.49:52
Joel Ward challenges Jamie Vardy unfairly and gives away a free kick. Anthony Knockaert restarts play with the free kick.48:30
Damien Delaney gives away a free kick for an unfair challenge on Wes Morgan. Direct free kick taken by Kasper Schmeichel.47:51
Inswinging corner taken left-footed by Mile Jedinak from the right by-line, Wes Morgan manages to make a clearance.45:52
Corner taken left-footed by Anthony Knockaert, clearance by Damien Delaney.45:01
The second half kicks off.45:00 +2:52 Half time
Half Time The referee blows for half time.43:59
Corner taken right-footed by Anthony Knockaert from the left by-line, Damien Delaney makes a clearance.42:10
Inswinging corner taken by Anthony Knockaert.40:22
The referee blows for offside against Wes Morgan. Free kick taken by Julian Speroni.39:29
Corner taken by Anthony Knockaert from the left by-line.39:00
Inswinging corner taken from the right by-line by Anthony Knockaert.35:57
Kagisho Dikgacoi restarts play with the free kick.35:57 Booking
Booking Jamie Vardy receives a caution.35:45
Jamie Vardy challenges Wilfried Zaha unfairly and gives away a free kick.34:22
Zak Whitbread gives away a free kick for an unfair challenge on Wilfried Zaha. Direct effort from the free kick comes in from Mile Jedinak, blocked by Anthony Knockaert.32:45
Foul by Ritchie De Laet on Wilfried Zaha, free kick awarded. Mile Jedinak takes the free kick.31:56 Substitution
Substitution Matty James joins the action as a substitute, replacing Lloyd Dyer.30:41
Handball decision goes against Zak Whitbread. Free kick crossed left-footed by Mile Jedinak, save by Kasper Schmeichel.30:02
Inswinging corner taken by Anthony Knockaert, clearance by Peter Ramage.28:38
Corner from left by-line taken by Anthony Knockaert.27:34
Assist on the goal came from Yannick Bolasie.27:34 Goal scored
Goal! - Peter Ramage - Leicester 0 - 2 C Palace Peter Ramage finds the back of the net with a headed goal from close in. Leicester 0-2 Crystal Palace.26:57
Yannick Bolasie takes the inswinging corner,26:00
Long range shot by Wilfried Zaha goes wide right of the target.22:52
The assist for the goal came from Mile Jedinak.22:52 Goal scored
Goal! - Damien Delaney - Leicester 0 - 1 C Palace Damien Delaney gets on the score sheet with a goal from inside the box low into the middle of the goal. Leicester 0-1 Crystal Palace.22:32
Inswinging corner taken from the right by-line by Mile Jedinak,21:50
Corner taken left-footed by Mile Jedinak from the right by-line, clearance by Danny Drinkwater.20:32
Shot from just outside the penalty area by David Nugent misses to the left of the target.18:06
Jamie Vardy challenges Damien Delaney unfairly and gives away a free kick. Julian Speroni restarts play with the free kick.16:21
The ball is sent over by Wilfried Zaha, save by Kasper Schmeichel.15:44
Inswinging corner taken by Yannick Bolasie.15:04
Andy King produces a header from inside the area that goes over the bar.14:20
Corner from the right by-line taken by Anthony Knockaert, Damien Delaney manages to make a clearance.12:26
Corner taken short by Anthony Knockaert.6:40
David Nugent takes a shot. Julian Speroni makes a save.2:09
The official flags Glenn Murray offside. Indirect free kick taken by Wes Morgan.0:50
Shot from close in by Yannick Bolasie misses to the left of the goal.0:00
The ref blows the whistle to begin the match.
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