Luke Shaw's season could be over after suffering a badly bruised foot against Swansea, sources have told ESPN FC.
The Manchester United defender lasted just nine minutes of the 1-1 draw at Old Trafford before being replaced by Antonio Valencia. The left-back, 21, was injured in a collision with Swansea forward Jordan Ayew.
And it is feared he could now miss United's final six games of the season, starting with the Europa League semifinal first leg with Celta Vigo in Spain on Thursday. It could also rule Shaw out of a possible Europa League final in Stockholm next month should they advance past Celta.
Jose Mourinho admitted after the draw with Swansea that Shaw could have suffered a significant injury.
"I think Luke Shaw's must be a big injury, because to leave the pitch after nine minutes, I am expecting a very big injury," he told the BBC.
"At the moment, we can walk from the bed to the toilet and break a leg."
It is the latest in a series of setbacks for Shaw this season. He has been publicly criticised by Mourinho, most recently following the 1-1 draw with Everton last month when the United manager said the England international had to "grow up, mature and understand the game better."
After two months without starting a game between November and January, Shaw has worked his way back into Mourinho's plans. His start against Swansea was his third in April, taking his tally for the season to 17.
Sunday's matchday programme contained an interview with Shaw in which he said: "I'm really disappointed [the season] is coming to an end. I wish it was the start of the season and I had the whole season in front of me."
United are having to deal with a growing injury list as the season reaches its conclusion. Zlatan Ibrahimovic, Marcos Rojo and Timothy Fosu-Mensah are long-term absentees while Phil Jones, Chris Smalling and Eric Bailly are also currently sidelined.
Mourinho faces the prospect of travelling to Spain this week with just 14 senior outfield players available.