Borussia Dortmund defender Sokratis Papastathopoulos will miss the second leg of the Europa League round-of-32 tie against Porto and the Bundesliga clash with Bayern Munich due to an adductor injury.
The Greek centre-back picked up the injury during Dortmund's 1-0 win against Bayer Leverkusen on Sunday and was replaced 13 minutes from time at the BayArena.
Tests on Monday confirmed the 27-year-old will be out for up to three weeks and will miss Dortmund's clash with Porto in Portugal.
Thomas Tuchel's side lead 2-0 from the first leg but the Dortmund boss will also be without Sokratis for several Bundesliga matches, including the visit of leaders Bayern Munich on March 5.
Dortmund trail the holders by eight points and defeat at Signal Iduna Park will all but seal Bayern's fourth successive league title.
Sokratis is also set to miss games against Hoffenheim, Darmstadt and Mainz over the coming weeks, with Neven Subotic likely to replace him.