An extraordinary error by goalkeeper Jamal Blackman proved costly for Sheffield United, who lost top spot in the Sky Bet Championship after being beaten 1-0 at QPR.
Idrissa Sylla's early goal clinched a second home victory in three days for Ian Holloway's side, who beat high-flying Wolves on Saturday.
However, Wolves capitalised on United's slip-up at Loftus Road by winning at Norwich to move back to the top of the table.
There seemed to be little danger for United when Blackman came to gather Jordan Cousins' ball into the box in the fourth minute.
But the on-loan Chelsea man misjudged the bounce of the ball and then dropped it after colliding with team-mate Cameron Carter-Vickers, gifting the waiting Sylla a simple tap-in.
Blackman, who appeared to land awkwardly, was then carried off on a stretcher following several minutes of treatment on the pitch.
Luck was on Rangers' side again when Jack O'Connell missed a sitter, steering his shot wide of the target when found unmarked by Paul Coutts' left-wing
And United then missed another great chance to equalise, this time when former QPR striker Leon Clarke fired over after being picked out by David Brooks' cross from the left .
Clarke was also denied at close range by Alex Smithies, who dived at his feet to save following more good work on the left by the dangerous Brooks.
QPR, who battled spiritedly throughout, also threatened during a lively first half. Simon Moore, who replaced Blackman, back-pedalled to just about keep out Sylla's first-time strike from long range following Conor Washington's neat lay-off.
The Rangers front pairing combined again just after the half-hour mark when Sylla headed over from Washington's beautifully-delivered cross.
Early in the second half, Sylla directed a header narrowly wide and United made a change in attack, bringing on Billy Sharp for the ineffective Clayton Donaldson.
Sharp was soon involved in the action, testing Smithies with a low shot the Rangers keeper was down quickly to hold.
Sharp also crossed from the left for Clarke, who nodded into the net but was offside.
At the other end, Massimo Luongo curled an effort wide and R's substitute Jamie Mackie blasted over after being set up by the excellent Luke Freeman, who caused United constant problems.