Toulon - Australian playmaker Matt Giteau has been ruled out for at least three weeks, Toulon coach Bernard Laporte said on Friday ahead of his team's crucial string of European Cup pool matches.

Giteau has been struggling with a groin injury since last season's Top 14 semi-final against Stade Francais, Laporte said.

"Apparently it's not a groin strain," the coach said. "But when he plays, he suffers after half-time."

Quade Cooper will likely replace Giteau against Bath in the European Cup on Sunday, while Frederic Michalak's comeback from injury could be hurried through to provide extra cover.

Toulon are three-time defending champions in the tournament, but the match against Bath is a game both sides must win or almost certainly see their knock-out hopes end.

Both have two wins and a defeat from three games but trail Pool 5 leaders Wasps by six points. As neither side have picked up any bonus points yet, defeat would make winning the group virtually impossible while also rendering the chances of taking one of the two qualifying second place finishes negligible.