Lyon have confirmed that Houssem Aouar has tested positive for Covid-19 ahead of the opening game of the 2020-21 Ligue 1 season.
Rudi Garcia was forced to leave a key performer out of his plans for a meeting with Dijon at the Groupama Stadium on Friday night.
The French playmaker was the only player in the Lyon squad to test positive for coronavirus after the club's latest round of medical checks, and has been put into quarantine for the next 14 days.
Lyon confirmed the news in an official statement on their website, which reads: "Olympique Lyonnais confirms to have organised, on Thursday 27 August, a new test of all its players and professional staff in anticipation of the match against Dijon at Groupama Stadium.
"The results received this morning by the medical management of the club revealed that Houssem Aouar is the only player in the squad to have tested positive for Covid-19.
"As soon as the results were made known, Houssem was put into isolation for a fortnight while still being completely asymptomatic.
"Olympique Lyonnais can also confirm that the contamination of the player occurred outside the club.
"Houssem Aouar will return to training with the first-team squad in 10 to 15 days, depending on his next follow-up tests."
Aouar will not be eligible to feature for Lyon in their next outing at Bordeaux on September 11, and has also been removed from Didier Deschamps' France squad for UEFA Nations League fixtures against Sweden and Croatia, which are set to take place on September 5 and September 8, respectively. He has been replaced by Nabil Fekir of Real Betis.
Aouar was called up to Les Bleus for the first time, along with Dayot Upamecano of RB Leipzig and Rennes teenager Eduardo Camavinga.
He will, however, be available for selection again when Garcia's men take in a trip to Montpellier on September 15, pending a clean bill of health.
Lyon are not the only club in Ligue 1 to see their preparations for the new campaign disrupted by Covid-19, with Marseille forced to reschedule a clash with Saint-Etienne last week after announcing four positive cases within their squad.