Former Newcastle United target Daniel Sturridge limped out of West Bromwich Albion's defeat to Chelsea.
The Liverpool striker turned down a move to St James's Park and signed for Alan Pardew's side on loan late in last month's transfer window.
Sturridge limped off the pitch against former club Chelsea last night.
Antonio Conte's Premier League champions beat basement club West Brom 3-0. The result left Pardew's side eight points behind 13th-placed Newcastle.
"We've got to hope Daniel's injury isn't too bad," said former Newcastle manager Pardew.
"He was distraught. The way he's worked at our place has been of the highest order. He's absolutely devastated, because he wants this period to be a success."
United signed Islam Slimani on loan from Leicester City after missing out on Sturridge, whose Liverpool career has been interrupted by a series of injuries.
Slimani arrived on Tyneside with a minor groin problem and could make his debut against Bournemouth later this month.
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