Didier Ya Konan will miss German club Hanover's pre-season training camp.
The Ivory Coast striker suffered a torn harmstring.
Hanover are holding a nine-day camp in the Austrian town of Bad Radkersburg, but the striker will remain behind to receive treatment and begin rehab work.
''For us and the player, this diagnosis is of course a huge disappointment," said Hanover coach Mirko Slomka.
"But we know Didier is in good hands and can start his intensive rehabilitation care."
Ya Konan was Hanover's top-scorer last season, netting 14 goals in 28 German league games as his side finished fourth in the table to qualify for the Europa League.
Hanover begin their Bundesliga campaign for the new season when they host Hoffenheim on 6 August.