Nigel Pearson's City opened up a three-point lead at the summit by registering their 12th win in 17 games, courtesy of a Jamie Vardy double and Lloyd Dyer's sixth goal of the season.
Meanwhile, Burnley's first league defeat in 13 matches came at the John Smith's Stadium as Huddersfield Town completed a 2-1 victory over Sean Dyche's side.
Michael Duff's late red card added to the misery for Burnley, who have lost top spot for the first time since the start of October.
QPR looked on course for another victory thanks to Charlie Austin's first-half goal at Doncaster Rovers, but Theo Robinson and Paul Quinn netted in a shock comeback.
Ricardo Fuller scored in the sixth minute and Dan Gosling struck with 17 minutes remaining to send Dave Jones' side to a third consecutive defeat.
Gary Johnson's Yeovil Town recorded only their third victory of the season, ending a run of three straight losses with a 3-0 triumph at Watford.
Byron Webster, Ishmael Miller and Joe Edwards were on target and Yeovil's win dropped Barnsley to the foot of the table as David Flitcroft's side suffered a 3-0 home reverse at the hands of Birmingham City.
Tommy Spurr's goal on the stroke of half-time was enough to earn all three points and end Leeds' run of three consecutive wins.
The day's early game saw two south-coast clubs go head-to-head, but Bournemouth and Brighton and Hove Albion could not be separated in a 1-1 draw.
