Iran international striker Sardar Azmoun could miss the World Cup after a calf injury sustained on club duty at Bayer Leverkusen left him sidelined for six to eight weeks.
"Sardar Azmoun suffered a torn right calf muscle on Tuesday evening during the warm-up before the 2-0 defeat at FC Porto in the Champions League," Bayer Leverkusen said in a statement.
The 27-year-old's estimated time of absence will be between six and eight weeks, the club said.
The World Cup in Qatar gets under way on20 November with Iran facing England in their opening match the following day.
Iran also face Wales and the United States in Group B.
Azmoun has an impressive record of 41 goals from his 65 international appearances.
The centre-forward star has been a high-profile supporter of the protests inside Iran sparked by the death of Mahsa Amini.
At least 92 people have died in clashes, according to the Oslo-based Iran Human Rights. The official toll has been put at around 60, including 12 members of the security forces.