Gloucester number eight Zach Mercer will be out for a "few months" after having an operation on an ankle injury.

Gloucester next face Bath at home in a West Country derby on Friday.

However, England winger Jonny May and Wales' Louis Rees-Zammit are both in contention to return following the World Cup.

Argentina trio Santiago Carreras, Matias Alemanno and Mayco Vivas, and Italy scrum-half Stephen Varney, are also back at Kingsholm in training.

Mercer joined Gloucester this season from Montpellier and had played in three Premiership games this season before being forced off early in the defeat by Saracens last month.

"He got caught in a tackle at the beginning of the Saracens game, there were like three people that fell on him at the same time - it's one of those injuries and he's going to be out for a few months," director of rugby George Skivington told BBC Radio Gloucestershire.

"We could have strapped him up and tried to put him out but that's not how we do it here and I don't think that's the responsible thing, to bring him over here and ask him to limp on and see what happens.

"We've taken the action of getting it right and making sure that when he comes back he'll be 100%."

Mercer's back-row team-mate Ackermann has yet to play in the league this season because of the nerve injury which Skivington said is "not coming along as quick" as the team would have liked.

Rapava-Ruskin meanwhile, faces an unknown period out, with the team pulling him from the starting 15 at the last minute before their most recent defeat by Sale.

"He's got a bit of a random injury that we're not 100% certain what it is, it keeps flaring up on us and we keep having to pull him out." Skivington added.

"We need to nail down what that is and put a plan together."