Ousmane Dembele began his recuperation following his return to Barcelona after undergoing surgery on a torn hamstring.
The France international travelled to Helsinki for an operation on the injury, which he suffered on his full league debut for the club against Getafe on Saturday.
He is expected to be out for up to four months, though there has been talk of him returning earlier.
Dembele joined Barca from Borussia Dortmund last month after Neymar left Camp Nou to join Paris Saint-Germain. Barca paid €105million plus a reported €40m in add-ons to sign the 20-year old France international.