Tony Pulis has revealed that loanee Sam McQueen is set for an extended spell on the sidelines - and could be forced to return to Southampton.
The wing-back was stretchered off during Middlesbrough's 1-0 win over Crystal Palace in the Carabao Cup, with Pulis fearing the worst.
And it has now been confirmed that the 23-year-old is set for a long spell out after scans revealed a cruciate ligament injury in the loanee's knee.
Pulis confirmed the news ahead of the visit to Stoke City this weekend, and also claimed that the full-back could return to parent club Southampton for treatment.
"Sam's news is not very good," said the Middlesbrough boss.
"He's done his cruciate ligament in his knee so I don't think we're going to have Sam available for a long time.
"I think the doc is talking to the medical people at Southampton now and they'll decide whether Sam stays up here to recover or whether he returns to his mother club."
McQueen may not be the only Middlesbrough player absent this weekend either, with a sickness bug having swept its way through the Boro squad.
Pulis confirmed that changes were likely at Stoke, but wouldn't confirm who was missing.
"There will be a few changes because of injuries and suspensions, so the ones we call on we hope they'll go out there and give it their best," add Pulis.
"With the sickness bug we've had, the doctor had a couple in a little bit earlier today to see how they are.
"We'll go through that and then pick the team from there."