Kasper Schmeichel's injury-time penalty save helped Leicester move up to second place in the Championship as a David Nugent strike saw off Middlesbrough.
Leicester hit the woodwork four times before ex-England international Nugent met a flick-on from strike partner Chris Wood with a crisp half-volley.
Anthony Knockaert's drive hit the bar and then post, while the Boro frame also denied Michael Keane and Wood.
Schmeichel kept out Marvin Emnes' penalty as the visitors remained fifth.
Pearson's Boro past
Leicester boss Nigel Pearson remains a cult hero at Middlesbrough after captaining the Teesside club to Premier League promotion and two Wembley cup finals in the 1990s.
The Dane flung himself low to his left to push away the substitute's effort and cap a miserable day for Tony Mowbray's men.
The game was delayed by 15 minutes after the Middlesbrough players and staff were forced to walk the final part of their journey to the King Power Stadium because of heavy traffic in snowy weather.
But the less than ideal preparation did not seem to affect the visitors as they more than matched the in-form hosts during an entertaining first-half.
Leicester had won their previous three league games going into the match, scoring 11 goals in the process, and both teams knew they would move into the automatic promotion places with a victory.
Middlesbrough enjoyed plenty of attacking possession in the opening hour, though their goal also led a charmed life as the Foxes hit the woodwork on three occasions.
Knockaert hit a thunderous strike that beat Boro keeper Jason Steele but the ball hit the underside of the crossbar and bounced on the goalline before striking the right-hand post.
Leicester boast the meanest defence in the Championship having conceded just 23 goals in their opening 28 matches.
Keane's header looped on to the away crossbar in first-half stoppage time before Wood, who has scored six goals in three Leicester appearances since joining in a £1m deal from West Bromwich Albion, hit the woodwork with a far-post header.
But Middlesbrough could have opened the scoring after 36 minutes when Paul Konchesky blocked Rhys Williams's pullback from a tight angle after the away skipper had rounded Schmeichel.
Schmeichel denied the visitors again seconds later when he smartly blocked Andre Bikey's close-range header, but his finest stop came in the second minute of added time.
Foxes substitute Jamie Vardy inexplicably hacked down Williams, giving Emnes the opportunity to move Boro into fourth, but Schmeichel ensured Leicester kept their fifth clean sheet in six league matches.
Leicester manager Nigel Pearson:
"It feels great to be second in the league. The players applied themselves well tonight.
"In the second half we pushed the full-backs forward more and took more chances going forward.
"I think we had the better chances and it was a good game."
Middlesbrough manager Tony Mowbray:
"I'm unbelievably disappointed - I thought we did enough not to lose the game. We created more than enough chances to get something from the game against a good Leicester side who have been scoring freely.
"But we didn't stick the ball in the back of the net and goals change games."
Live Text Commentary
Full Time The referee blows his whistle to end the game.90:00 +3:26
Foul by Chris Wood on Seb Hines, free kick awarded. Jason Steele takes the free kick.90:00 +1:37
Grant Leadbitter takes a shot. Wes Morgan gets a block in. Inswinging corner taken from the right by-line by Emmanuel Ledesma. Rhys Williams takes a shot from long distance which goes wide of the right-hand post.90:00 +1:10
Short corner taken by Emmanuel Ledesma from the right by-line.90:00 +1:00 Penalty
Placed penalty taken by Marvin Emnes saved by Kasper Schmeichel. Leicester 1-0 Middlesbrough.89:50
Jamie Vardy gives away a Penalty for an unfair challenge on Rhys Williams.88:02
Effort from inside the area by Jamie Vardy misses to the left of the goal.87:36
Lukas Jutkiewicz takes a shot. Save made by Kasper Schmeichel.85:02
Unfair challenge on Rhys Williams by Jamie Vardy results in a free kick. Direct free kick taken by Jason Steele.82:38
Unfair challenge on Rhys Williams by Jamie Vardy results in a free kick. Rhys Williams takes the free kick.82:38 Substitution
Substitution David Nugent leaves the field to be replaced by Jamie Vardy.80:41 Substitution
Substitution (Leicester) makes a substitution, with Andy King coming on for Ben Marshall.78:27
Lloyd Dyer takes a shot. Save by Jason Steele.77:59
Corner taken left-footed by Emmanuel Ledesma, clearance by Ritchie De Laet.75:23
Emmanuel Ledesma takes the inswinging corner, Michael Keane manages to make a clearance. Shot by Kevin Thomson from outside the box goes over the net.75:23 Substitution
Substitution (Leicester) makes a substitution, with Lloyd Dyer coming on for Anthony Knockaert.73:18
Inswinging corner taken left-footed by Emmanuel Ledesma, save by Kasper Schmeichel.72:28
The assistant referee signals for offside against David Nugent. Jason Steele takes the free kick.71:25 Substitution
Substitution Scott McDonald leaves the field to be replaced by Lukas Jutkiewicz.71:25
Scott McDonald produces a left-footed shot from inside the area that clears the crossbar.
Assist by Chris Wood.69:59 Goal scored
Goal! - David Nugent - Leicester 1 - 0 Middlesbro David Nugent finds the net with a goal from just inside the area to the bottom left corner of the goal. Leicester 1-0 Middlesbrough.68:22
Andre Bikey challenges Chris Wood unfairly and gives away a free kick. Free kick taken by Paul Konchesky.68:22 Substitution
Substitution Marvin Emnes joins the action as a substitute, replacing Josh McEachran.68:22
Ben Marshall produces a right-footed shot from deep inside the penalty area which goes wide of the left-hand post.65:44
Shot by Kevin Thomson from outside the box goes high over the target.64:14
David Nugent takes a shot. Seb Hines gets a block in.63:23
The official flags Chris Wood offside. Jason Steele takes the indirect free kick.63:04
The assistant referee signals for offside against Scott McDonald. Kasper Schmeichel takes the indirect free kick.62:27
David Nugent is caught offside. Jason Steele restarts play with the free kick.60:55
Paul Konchesky produces a cross, Andre Bikey makes a clearance.60:38
Ritchie De Laet delivers the ball, Andre Bikey makes a clearance.57:17
Emmanuel Ledesma produces a strike on goal direct from the free kick.57:17 Booking
Booking Booking for Michael Keane for unsporting behaviour.57:12
Handball by Michael Keane.55:28
Free kick awarded for a foul by Kevin Thomson on Paul Konchesky. Michael Keane takes the direct free kick.55:04
Header from inside the area by Chris Wood bounces off the post.54:15
Josh McEachran fouled by Danny Drinkwater, the ref awards a free kick. Direct free kick taken by Faris Haroun.53:20
Effort from inside the area by Emmanuel Ledesma misses to the right of the goal.51:22
Ben Marshall produces a right-footed shot from outside the penalty box and misses right.49:27
Emmanuel Ledesma delivers the ball from the free kick left-footed from right wing, save by Kasper Schmeichel.49:27 Booking
Booking Booking for Paul Konchesky for unsporting behaviour.49:10
Free kick awarded for an unfair challenge on Emmanuel Ledesma by Paul Konchesky.48:04
Emmanuel Ledesma takes a shot. Wes Morgan gets a block in.47:14
Inswinging corner taken left-footed by Anthony Knockaert from the right by-line to the near post, Kevin Thomson manages to make a clearance.46:31
Grant Leadbitter has an effort at goal from the edge of the box that misses to the right of the target.45:45
Emmanuel Ledesma fouled by Paul Konchesky, the ref awards a free kick. Free kick taken by Emmanuel Ledesma.45:01
The referee gets the second half underway.45:00 +1:44 Half time
Half Time The ref blows to end the first period.45:00 +0:35
David Nugent takes a shot. Jason Steele makes a save. Corner from right by-line taken by Anthony Knockaert. Michael Keane takes a shot.45:00 +0:14
Faris Haroun challenges Danny Drinkwater unfairly and gives away a free kick. Free kick taken by Wes Morgan.44:37
Chris Wood is flagged offside by the assistant referee. Indirect free kick taken by Jason Steele.42:23
Inswinging corner taken by Ben Marshall from the left by-line, Seb Hines manages to make a clearance. Ben Marshall takes the inswinging corner, save made by Jason Steele.41:28
Ben Marshall crosses the ball, save made by Jason Steele.39:35
Effort from the edge of the box by Anthony Knockaert goes wide of the right-hand upright.39:01
Matty James takes a shot. Andre Bikey gets a block in.37:17
Seb Hines gives away a free kick for an unfair challenge on Anthony Knockaert. Ben Marshall fires a strike on goal direct from the free kick, save made by Jason Steele. Josh McEachran gives away a free kick for an unfair challenge on Danny Drinkwater. Danny Drinkwater takes the free kick.36:17
Scott McDonald takes a shot. Kasper Schmeichel makes a save. Corner taken right-footed by Grant Leadbitter to the near post, Andre Bikey takes a shot. Save made by Kasper Schmeichel.35:13
Inswinging corner taken from the right by-line by Emmanuel Ledesma, save by Kasper Schmeichel.32:31
Free kick awarded for an unfair challenge on Danny Drinkwater by Grant Leadbitter. Danny Drinkwater takes the direct free kick.29:44
Free kick awarded for a foul by Paul Konchesky on Emmanuel Ledesma. Direct free kick taken by Jason Steele.28:03
Inswinging corner taken by Ben Marshall.27:35
Anthony Knockaert takes a shot.26:25
Shot by Scott McDonald from outside the box goes over the net.25:17
Grant Leadbitter takes a shot. Blocked by Wes Morgan.23:29
David Nugent takes a shot. Blocked by George Friend. Inswinging corner taken by Anthony Knockaert from the right by-line.22:38
Grant Leadbitter takes a shot. Michael Keane gets a block in. Corner taken right-footed by Grant Leadbitter to the near post, clearance made by Danny Drinkwater.21:31
Unfair challenge on George Friend by Chris Wood results in a free kick. Jason Steele takes the direct free kick. Emmanuel Ledesma challenges Danny Drinkwater unfairly and gives away a free kick. Direct free kick taken by Paul Konchesky.20:40 Substitution
Substitution Kevin Thomson joins the action as a substitute, replacing Justin Hoyte.19:10 Booking
Booking Emmanuel Ledesma receives a caution.18:07
Ben Marshall takes a inswinging corner from the left by-line played to the near post, Grant Leadbitter manages to make a clearance. Inswinging corner taken by Ben Marshall, Jason Steele makes a save.17:47
Rhys Williams concedes a free kick for a foul on Wes Morgan. Matty James takes the free kick.16:28
Scott McDonald has an effort at goal from deep inside the area missing to the right of the target.15:03
Corner taken right-footed by Ben Marshall to the near post, Justin Hoyte makes a clearance.14:20
Chris Wood takes a shot. Save by Jason Steele.12:58
David Nugent takes a shot. Save by Jason Steele. Inswinging corner taken left-footed by Anthony Knockaert from the right by-line, Rhys Williams manages to make a clearance. Inswinging corner taken from the left by-line by Ben Marshall.10:09
Rhys Williams fouled by Paul Konchesky, the ref awards a free kick. Direct free kick taken by Justin Hoyte.6:48
Shot from deep inside the area by Scott McDonald clears the crossbar.6:01
Ben Marshall takes a shot. Save by Jason Steele.4:51
Unfair challenge on Matty James by Seb Hines results in a free kick. Danny Drinkwater takes the direct free kick.4:29
The ball is delivered by Scott McDonald, Michael Keane makes a clearance.0:00
The referee gets the match started.
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