Manchester United forward Alexis Sanchez has suffered a hamstring injury.
United have said the Chile forward sustained the problem in training on Thursday.
"It requires further investigation to confirm severity," a United spokesperson said.
The injury will further add to Sanchez's disappointing time at Old Trafford.
He moved north from Arsenal in the January transfer window as part of a swap deal with Henrikh Mkhitaryan but his impact has been limited.
The 29-year-old has scored just four goals for United in 30 appearances and has found a regular first-team place hard to come by.
He was omitted from Tuesday's Champions League win over Young Boys entirely and now appears set for more time on the sidelines.
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