QPR caretaker boss John Eustace fears Jordan Cousins could face a long spell out with a serious knee injury after he was stretchered off during the home defeat against Blackburn.
Rangers were beaten 2-1 at Loftus Road, where Cousins was in obvious distress as he was carried from the pitch early in the second half.
He fell awkwardly after an accidental collision with team-mate Bright Osayi-Samuel near the halfway line.
The injury will be assessed over the next 24 hours by the Sky Bet Championship club but the initial signs are not good.
Eustace said: "There's no news at the moment but it certainly looks a bad one. We'll have to wait and see on that."
Danny Graham's 22nd-minute penalty put Blackburn ahead and Bradley Dack doubled their lead just 29 seconds into the second half.
Matt Smith headed in Luke Freeman's injury-time cross to pull a goal back for QPR, who are still not mathematically safe from relegation.
Winger Osayi-Samuel was lively but missed chances, while Rangers were punished for some sloppy defending.
Eustace, placed in charge following the recent sacking of Steve McClaren, said: "I'm disappointed with the performance but the attitude of the lads was fantastic. They kept going.
"The most disappointing thing was the goals we conceded – poor decision-making. We also created a lot of chances and it's disappointing we didn't take them.
"We've made two really poor decisions for the goals and started the second half so sloppily. But the attitude of the boys was good, which it is every week.
"Blackburn are a very streetwise team and we knew it would be tough for us today, but we needed to take the chances we created.
"We're down to the bare bones and had to change the back four, but that's certainly not an excuse. We weren't good enough.
"It's up to the players who put the shirt on to go out and play well."
Blackburn manager Tony Mowbray felt his side were rewarded for their attacking approach.
"We came to just to play today, play with two strikers and two wide players," he said.
"We got in behind them a lot, had the better chances, and I think the result was right. Their directness gave us some problems but we deserved to win.
"Dack and Graham scored and that's 17 and 16 goals for them this season, which isn't a bad return.
"It's Bradley's first season in the Championship, so he's done exceptionally well.
"Let's just keep going, see if we can finish the season strongly and get some momentum for next year."
Mowbray made a change in goal, replacing the out-of-form David Raya with Jayson Leutwiler. Both have been told to expect the arrival of a new keeper this summer.
Mowbray explained: "It was time to give the goalkeeper (Leutwiler) a chance really.
"I sat David Raya down this week and told him 'time to change'.
"David's dropped below the standards he set last season. I still think he's got lots to learn. He's a work in progress and it won't do him any harm to sit on the bench.
"If your number two goalie never gets a game you're never going to know (if he's good enough) if your number one gets injured and he has to go and play.
"I've told them that goalkeeper is one of the areas that we'll be looking at in the summer to try to strengthen and create better competition."