Portugal will be without Fabio Coentrao against Northern Ireland in Lisbon on Tuesday after the midfielder was hurt in Portugal's defeat to Russia on Friday, coach Paulo Bento said.
Real Madrid's Coentrao limped off after 20 minutes of the 1-0 loss following a tough tackle and was substituted.
"He will not play in the next game," Bento said without specifying the nature of the injury.
"We haven't spoken to the doctors yet."
Coentrao's absence could spark a chain of changes to the squad for the Northern Ireland game, Bento suggested.
"We will think before Tuesday. There may be changes because of the injury Coentrao received," he said.
The 24-year-old Coentrao has 28 caps for his country.