Real Sociedad could be without the services of key player Mikel Oyarzabal for both of their Europa League last-32 matches with Manchester United.
The La Liga club will take on the Red Devils in the first leg of their knockout affair in Turin next Thursday before travelling to Old Trafford for the second leg on February 25.
Oyarzabal has been diagnosed with a hamstring problem, though, and it is thought that the Spain international will be absent from both games with the 20-time English champions due to the nature of the issue.
"Mikel Oyarzabal has presented with tendinopathy in the proximal hamstring tendons of the right thigh. He has begun physical therapy treatment. A return to action will depend on the evolution of his symptoms," read an official statement from the Basque outfit.
The 23-year-old has been in impressive form for La Real during the 2020-21 campaign, scoring 12 times and contributing six assists in 25 appearances in all competitions.
Imanol Alguacil's side will face Getafe in La Liga on Sunday, while United are in Premier League action on the same day against West Bromwich Albion.
