Lyon midfielder Clement Grenier has been ruled out for six to eight weeks with a recurrence of a long-standing groin injury, the French club announced on Friday.

The France international will undergo an operation in the next few days in the hope of healing an ongoing problem that caused him to miss much of Lyon's Ligue 1 run-in last season and forced him out of the World Cup in Brazil.

Grenier made his competitive return on Thursday, coming on as second-half substitute, in a shock 2-1 home defeat to Romanian side Astra Giurgiu in the first leg of the Europa League play-off round.

Lyon boss Hubert Fournier's decision to throw on Grenier with 15 minutes remaining backfired with the midfielder conceding a penalty that led to the visitors' winning goal before finishing the contest doubled over in pain.

"We put him in the game. There was a one in two chance (of a relapse). It didn't work out in our favour. It's not the worst thing though because it means he will undergo an operation," said Fournier.

"He will be sidelined for six to eight weeks. Afterwards things will be resolved because for the past so many months we've been carrying a player who isn't 100 per cent," he added.