Neil Warnock's unbeaten start as QPR manager came to an end as a late Gylfi Sigurdsson penalty was enough to give Reading yet another Coca-Cola Championship victory.
Rangers looked like frustrating the resurgent Royals to hang on for a point despite playing with 10 men for the entire second half until Sigurdsson's 85th-minute spot-kick.
QPR had the best of the first half only to have defender Damion Stewart sent-off in the 45th minute for senselessly challenging Adam Federici as the goalkeeper took a quick drop-kick.
The visitors then produced a resolute rearguard display after the break.
But Brian McDermott's side kept going and earned their eighth win in their last nine league games to continue to climb the table.
The Royals won their penalty when Sigurdsson tricked his way into the area before being tripped and the Icelandic midfielder blasted the resulting spot-kick into the top corner.