Former England international Delon Armitage has been ruled out for the rest of the season with a serious knee injury.
Armitage was stretchered off during Lyon's 16-16 draw against Toulouse on Saturday after damaging the anterior cruciate ligaments in his left knee.
The 34-year-old will have surgery on Friday and is expected to be sidelined for at least 10 months.
A product of London Irish's academy and three-time European Cup winner with Toulon, Armitage won 26 caps for England, scoring seven tries. His last appearance came in the win over Scotland at the 2011 World Cup.
He joined Lyon from Toulon in 2016 and helped the club reach last season's Top 14 semi-finals.
Lyon will also be without captain Juilen Puricelli for up to eight weeks after he suffered a shoulder injury against Toulouse.
They are away to defending Top 14 champions Castres on Saturday.