Sadio Mane has been injured in a clash with Al-Nassr in the Saudi Professional League on Sunday.
The Senegal international sustained a knee injury and was stretchered off the pitch after being fouled by a player from Al-Nassr.
Mane, who plays for Liverpool in the Premier League, is expected to miss the remainder of the season.
Al-Nassr's manager, Paulo Sousa, has said that Mane will be out for "several weeks".
He added that the club will offer him medical treatment as soon as possible.
"We have lost one of our best players," Sousa told reporters.
"It's a big blow for us."
Mane has scored 15 goals in 26 appearances for Liverpool this season, helping them to win the Premier League title.
However, his absence could leave a gap in their attack.
Al-Nassr, meanwhile, were already struggling before Mane's injury.
They had lost four of their last six matches in all competitions and were bottom of the league table.
But they will now have to look elsewhere for their attacking options.