Preston moved up to third after a 2-1 success at the Walkers Stadium ended Leicester's unbeaten home run.
Mellor and Chaplow send Irvine's men up to third
Preston North End moved up to third in the table after a 2-1 success at the Walkers Stadium ended Leicester City's long unbeaten home run.
Neil Mellor gave the in-form Lilywhites a first-half lead and midfielder Richard Chaplow doubled the advantage midway through the second period.
Bruno Berner scored a late consolation for the Foxes, who were tasting defeat on their home patch for the first time in more than a year.
City dominated the early stages without really threatening Andy Lonergan's goal but Preston looked dangerous on the break.
Preston should have gone ahead in the 16th minute following good link-up play down the right between Mellor and Billy Jones.
Jones' low cross looked like being turned in by the unmarked Chris Sedgwick at the far post but the midfielder was slightly off balance when the ball reached him and he blazed his shot over the crossbar.
A Chaplow-led counter-attack could have quickly brought another goal for the visitors but his cross went straight into Chris Weale's arms.
After Matty Fryatt had curled a shot just wide, Weale was then called into more athletic action.
Mellor's cross from the left was headed goalwards by Chris Brown. The ball looked like looping into the corner but Weale plucked it from the air at full stretch at the last moment.
At the other end, Lonergan kept his side ahead by blocking Matt Oakley's shot with his feet. Paul Gallacher headed the rebound on to the roof of the net.
The opening goal came from a poor piece of defending from Richie Wellens in the 42nd minute. The former Doncaster playmaker inexplicably headed Wayne Brown's clearance back into his own penalty area instead of directing the ball clear.
Brown seized possession and showed quick feet to set up strike partner Mellor, who clinically steered the ball into the bottom corner from 15 yards.
Weale then kept his side in the game with a point-blank save to deny Mellor a minute before the break.
Dany N'Guessan should have done better than blaze his shot over the crossbar when set-up by Wellens early in the second half.
Preston doubled their lead after 66 minutes when Mellor broke from the edge of his own box.
Wayne Brown backed off and allowed the burly forward to reach the City box where he squared the ball for Chaplow to shoot underneath Weale.
Leicester were given hope in the 90th minute when Lonergan parried Gallacher's shot into Berner's path and the full-back returned the ball into the bottom corner.
The Foxes pushed for an equaliser throughout the four minutes of injury-time but it was not forthcoming.
