Manchester - Ander Herrera's lack of certainty over his future may have contributed to his ongoing injury problems, Manchester United manager Ole Gunnar Solskjaer said on Friday.
The midfielder has managed just 134 minutes of football since suffering a hamstring problem during the 0-0 draw against Liverpool on February 24.
Herrera came back for two matches - the FA Cup quarter-final defeat at Wolves and the Premier League home victory over Watford - before a thigh injury sustained in training forced him out of action again.
Paris Saint-Germain are believed to be interested in signing the 29-year-old, who is out of contract at Old Trafford at the end of this season.
Solskjaer has indicated that United are still in talks to try to keep Herrera at the club but suggested that the interest from elsewhere is not helping the player.
The manager was quick to emphasise that he was not questioning the midfielder's professionalism, adding that he hoped to have Herrera fit for the Premier League home matches against Manchester City and Chelsea in late April.
"Maybe the future might have been worrying him and that's part of the reason he's injured," said Solskjaer. "Who knows? He doesn’t know.
"Hopefully he can be available for Chelsea or City but I'm not sure. He got another muscle injury.
"He's been working really hard to get fit from the injury he sustained against Liverpool. Then he came back and got a different one here in training.
"He's been putting a lot of work in and that's come at a time where there are contract talks but that's ongoing, I can't really comment too much on how far they are down the line."
Solskjaer declined to offer a public assessment of United's chances of keeping Herrera at his pre-match press conference.
"I don't know how the talks have been going, but we've let him focus on his fitness," Solskjaer said. "He loves to play, so he's not very happy when he can't help his teammates. He is always giving his all, it doesn't matter if there are five weeks or five years on his contract."
Both Herrera and Alexis Sanchez will miss Saturday's Premier League home match against West Ham as United seek to revive their Champions League qualification hopes, while midfielder Nemanja Matic remains a doubt because of the illness that forced him to miss Wednesday's home defeat by Barcelona.
Sanchez has not played since sustaining medial knee ligament damage during the 3-2 Premier League win over Southampton on March 2 but has now resumed full training.
Solskjaer suggested that the Chile forward could make his squad for the second leg of their Champions League quarter-final against Barcelona next Tuesday.
United are in sixth place in the Premier League, three points outside the top four, having lost four out of five matches in all competitions since their remarkable victory over Paris Saint-Germain in Paris to reach the Champions League quarter-finals.
Their manager has set his team a target of finishing in the top three, suggesting they need to win five of their final six league matches in order to achieve it.
He said: "We need as many points as possible. I think if we get 15 we'll be in the top three because in those games hopefully we'll beat Chelsea.
"But now it's about West Ham and focusing on a good performance to give us three points. We want top three. Top four is also an aim if we don't get 15 - but we should aim for 15 points."