Nahki Wells' controversial goal gave QPR a 1-0 victory and dealt another blow to Leeds' promotion bid.
Wells netted after 20 minutes at the Kiyan Prince Foundation Stadium, where Patrick Bamford had a second-half penalty saved by home goalkeeper Liam Kelly and Kalvin Phillips was sent off late on.
Phillips was red-carded following a crude challenge on QPR midfielder Geoff Cameron in the 89th minute.
The pair have history, with Cameron having missed more than three months of last season because of an equally reckless challenge by Phillips when these clubs met at Elland Road in December 2018.
Phillips lost his cool towards the end of a hugely frustrating game for Leeds, whose defeat was their second in a row in the Sky Bet Championship and continued an alarming run which has seen them win just one of their past seven league matches.
With the likes of Brentford and Fulham breathing down their necks, and having run out of steam in last season's promotion race, the Yorkshire side have every reason to be worried.
They certainly had reason to be angry about Wells' winner.
Luke Ayling attempted to block Ebere Eze's free-kick and the Leeds defender inadvertently headed it towards Wells, who controlled the ball on his arm before firing past Kiko Casilla from close range.
The goal – Wells' 14th of the season and fifth in his past three matches – would certainly have been ruled out if VAR were operating in the Championship.
But luck was on Leeds' side when Wells missed a great chance to double Rangers' lead as he miscued after being found unmarked by another Eze free-kick.
Bamford then missed a chance for the visitors, shooting over with just Kelly to beat after Conor Masterson had misjudged keeper Casilla's long punt forward.
And Bamford was unable to score from the spot just after the hour mark.
He latched on to Ayling's pass and went down after minimal contact from Kelly, who had the last laugh by diving to his left and pushing away the striker's penalty.
Marcelo Bielsa's side dominated much of the second half but the penalty was by far their best chance to draw level.
Kelly held a long-range strike from Phillips and was relieved to see Pablo Hernandez's free-kick flash narrowly wide.
Rangers remained a threat on the counter-attack, with Eze and the in-form Bright Osayi-Samuel always a problem for the visiting defence.
