Middlesbrough striker Jeremie Aliadiere has suffered a setback in his recovery from a hamstring injury.
The young Frenchman has been out of action since picking up a hamstring injury against West Ham last month.
Aliadiere had targeted a return to action against Chelsea this weekend, but the former Arsenal ace looks set to miss out again after suffering a recurrence of the injury in training.
Discomfort"I had been running and sprinting and going well but I have been feeling some discomfort in training this week so I will have to take it easy," Aliadiere told the Northern Echo.
"I don't want to damage it again so it may be another week or so before I can start training. I don't think I have a chance of facing Chelsea.
"I am now looking at playing Manchester United a week later if I can. It's been very difficult for me.
"I'm disappointed because I have been feeling good in training and I'm a bit down about things now. I just want to be playing again."
Meanwhile, Middlesbrough starlet Nathan Porritt remains set on leaving the club, according to the player's agent.
The highly-rated midfielder has turned down the offer of a senior contract at Middlesbrough.
The news has alerted a number of clubs at home and abroad who have been keeping tabs on Porritt's progress at The Riverside.
Middlesbrough 's valuation of the 17-year-old is believed to have scared off some interested clubs, but foreign sides could land Porritt for a smaller fee courtesy of a Fifa tribunal.
Porritt's agent Peter Harrison has confirmed the England Under 17 international is seeking a move away from Teesside and that a number of clubs are chasing hi signature.
Another club"Nathan would like to try another club," Harrison told the Sunday Sun.
"He's got Stewart Downing and Adam Johnson in front of him at Boro.
"And he could end up abroad - there are clubs interested in him - where the compensation may be less.
"He didn't sign the contract and since then nobody from the club has approached him or said anything more to the lad about it.
"He's accepted the situation and is just getting his head down and training well.
"When the second year of his scholarship ends we will sit down and assess things.