Moses Odubajo has been ruled out for three months with a calf injury.
It means the 28-year-old, signed on a one-year deal last summer, might well have played his final match for QPR.
The lengthy lay-off could also have an impact on his ability to find a new club before the start of next season.
Rangers boss Mark Warburton initially hoped that Odubajo would make a quick return to action.
However, the problem is more serious than was initially thought, ruling the former Brentford man out of the final matches of the campaign.
“What looked like an innocuous injury for Mo has turned out to be a longer, more serious-grade injury,” said Warburton, whose team travel to Stoke this weekend and next Friday will be at home to Sheffield United.
“I thought he might not make the Stoke game but might be available for Sheffield United.
“But unfortunately it’s going to be a longer-term one than that. It’s very frustrating.”
Odubajo, who turns 29 in July, was brought in by Warburton on a free transfer, having previously played under him at Brentford.
He was beset by injuries prior to joining the R’s but has managed to make 33 appearances this season, including 23 Championship starts.
He will not be fit by the start of pre-season training, but Warburton hopes that will not affect Odubajo’s ability to secure a move.
“I hope not,” Warburton said.
“If anyone speaks to me, in terms of how many games he’s played for us and the impact he can have and the quality he can show, I’ve got nothing to hide about Moses.”