Erling Haaland will undergo more testing to determine the extent of muscle damage sustained in Borussia Dortmund's 3-2 victory against Hoffenheim on Saturday.
Haaland was pulled off in the second half at the PreZero Arena after taking a knock.
The Norway international will begin therapy this week for muscle difficulties and now faces a race to be healthy for Bayer Leverkusen's visit on February 6.
A Dortmund statement read: "Haaland was examined in detail on Sunday and Monday. According to the medical report, the Norwegian is suffering from muscular problems, which will require treatment and further examinations in the coming days.
"We hope that Erling will be back to full fitness as soon as possible and can get back to doing what he loves the most – scoring goals for BVB."
Haaland has 23 goals in all competitions for Dortmund this season. Among players from the top five European leagues, only Real Madrid's Karim Benzema (24) and Robert Lewandowski (34) have more entries.
Haaland, however, has the greatest minutes per goal ratio of 70.4 among players who have scored more than ten goals. With a goal every 71 minutes, Lewandowski is a close second.