French league leaders Lyon will be without key striker Alexandre Lacazette after he was forced off against Metz with a thigh injury, the club announced.

Lacazette, the league's leading scorer with 21 goals, limped off after 34 minutes of Sunday's 2-0 victory which saw Lyon go four points clear at the top of the table.

Coach Hubert Fournier confirmed that Lacazette would miss next week's trip to Monaco and was doubtful for the game against champions Paris Saint-Germain the following week.

"We'll have to wait for a full report from the club's medical staff before we know how long he will be out," Fournier said.

"We've got two important matches against title rivals and there's never a good time for these things to happen, but even less so now."

Lacazette went off shortly after opening the scoring from the penalty spot and was replaced by Maxwel Cornet.