John McGinn has been ruled out for three months with a fractured ankle - dealing a blow to Man Utd's transfer plans.
The Aston Villa midfielder was substituted after just eight minutes during his side's defeat to Southampton on Saturday.
He pressed Southampton's defence, blocking a clearance by Cedric, but landed awkwardly.
McGinn was carried off the field by Villa medical staff, with Marvelous Nakamba coming on in his place.
Villa boss Dean Smith said after the match: ""He has gone for an X-ray, it doesn't look good. He got his studs caught in the turf. We will wait and see."
The extent of his injury was then confirmed on Sunday.
The news will come as a blow to Villa, who slipped into the bottom three following the loss to the Saints.
McGinn has been ever-present for Villa this season, making 20 appearances in all competitions and scoring twice.
He has also played a pivotal role in Scotland's Euro 2020 qualifying campaign, but faces a battle to be fit in time for their play-off semi-final with Israel on March 26.
United had made McGinn a key target for when the January transfer window opened next month.
The 25-year-old has been linked with a £50 million move to United, but Red Devils boss Ole Gunnar Solskjaer will now be forced to pursue other targets if he wishes to bolster his midfield in January.
McGinn tweeted: "Thanks everyone for all the messages and support. Gutted but will be back before you know it."
Meanwhile United look set to be dealt another blow, as Christian Eriksen is reportedly prepared to snub a move to United for a second time.
Eriksen was a target for United in the summer, but failed in their pursuit.
The Dane is now set to turn down the chance to switch to Old Trafford in the hope of receiving a better offer from elsewhere.
Real Madrid are Eriksen's preferred destination, while Juventus have also been linked.
