QPR slipped to their second league defeat in a week following a 2-0 reverse at fellow promotion-chasers Nottingham Forest.
A goal either side of the half-time interval handed Billy Davies’ men the points.
Greg Halford headed home the opener just short of the half-hour mark, before Andy Reid added a controversial second with 10 minutes left on the clock.
Rangers made three changes to the side defeated by Leicester City at Loftus Road on Saturday.
Top scorer Charlie Austin missed out owing to a hamstring complaint, while Joey Barton served a one-match suspension following his sending off against the Foxes. Gary O’Neil (virus) was also unavailable.
Those absences meant that Bobby Zamora made a first start in over three months after a spell on the sidelines through injury, while Karl Henry and former Forest man Jermaine Jenas were also named in Harry Redknapp’s starting XI.
For Forest, ex-QPR ace Jamie Mackie was among the home starters.
The contest experienced a quiet start, with neither team able to create a clear-cut opening inside the first 15 minutes.
The first real opportunity of note arrived on 19 minutes – and what a chance it proved to be.
Fortunately for Rangers, the hosts spurned what was a fine opening. QPR surrendered possession just inside their own half and when Halford eventually found himself through on goal, Rob Green was forced into a smart low block.
A minute later, Halford wasted another opportunity, firing well over after good work from Henri Lansbury down the left.
Despite a slow start, chances were now more forthcoming.
In the 21st minute, Jenas saw a shot blocked after linking well with Zamora, while Benoit Assou-Ekotto’s long-range rasper was well held by Karl Darlow.
Three minutes later, Lansbury drilled a low effort just wide of the foot of the left-hand post.
Forest forged ahead in the 29th minute. Mackie and Djamal Abdoun exchanged passes down the left and when the latter crossed for Halford, he headed past a helpless Green from close range.
Rangers came within a whisker of equalising five minutes later. Niko Kranjcar drove at the home backline before curling a low effort just wide from 20 yards.
No further opportunities arrived until the second half – the first of which came in the 50th minute when Matty Phillips blasted over.
Before that, the R’s made a double substitution at the break. Junior Hoilett and Andy Johnson replaced Henry and Zamora respectively.
Those changes saw visitors QPR look much more dangerous going forward and Kranjcar’s teasing free-kick somehow evaded the head of Johnson, with the ball dropping just past the right-hand post.
Tom Carroll then forced Darlow into a fingertip save after taking control of a Phillips cross.
Halford missed a golden chance to double his – and Forest’s – tally in the 65th minute. Mackie’s cross from the right found the makeshift centre-forward unmarked from six yards, but he could only shoot straight at Green.
Rangers were hardly hanging on in the second period though Clint Hill did have to produce a goal-line clearance to deny the hosts a second goal in the 71st minute, following an effort from Jack Hobbs.
At the other end, only a deflection prevented Jenas from finding the target after a fierce shot from range.
QPR used their third and final substitution shortly after, with Yossi Benayoun brought on in place of Phillips.
This Championship affair became increasingly more open towards the climax and Forest sealed the win in controversial circumstances come the 80th minute.
A linesman flagged for offside against Halford following an Abdoun through pass – but when Reid stole through on goal and slotted home, the referee overturned the decision.
With all 11 Rangers players voicing their disapproval, referee Keith Stroud consulted his linesman for a lengthy period before confirming the goal.