England flanker Sam Underhill will miss the Nations Championship this autumn after rupturing his biceps in Bath’s opening Prem game away at Harlequins.

Underhill went off in the 48th minute of the win at The Stoop and was seen at the end of the game with strapping around his arm, which will require surgery later this week.

Bath expect the 30-year-old to be out until December or January, meaning he will miss a large portion of the domestic season as well as England’s three internationals against Australia, Japan and New Zealand in November.

Bath head of rugby Johann van Graan said he knew straight away the injury was serious, which was why he went immediately over to Underhill when he came off the pitch.

“There are a few types of injuries where I just want to know straight away because I know the impact that it has longer term and I always feel for the players, so that’s why I went straight down,” Van Graan told BBC Radio Somerset.

“At the time I thought, we need to wait for a scan but this could be a biceps rupture. The scan turned out to be exactly that.

“He will get operated on on Thursday, that’s a few months out of the game – not ideal from Sam’s point of view.”

Underhill has been capped 51 times by England and played in all five of their Six Nations matches this year.

However he missed the summer internationals against South Africa, Fiji and Argentina to have an operation on a shoulder injury.

“It’s always disappointing for every player when you get injured in a warm-up game, or round one, because you’ve just gone through a big pre-season,” Van Graan added.

“Injuries are part and parcel of this game. Sam has had a few big ones. I’m sure he’ll be back as soon as possible and [we’re] looking forward to welcoming him back whenever that is, whether it’s December or January.”

Bath are also without new signing Jamie Bhatti after he broke a forearm during pre-season. Fellow prop Vilikesa Sela is out until November with a toe injury also picked up in pre-season, while wing Will Muir has no return date yet after injuring his shoulder last season.

Ben Spencer and Louie Hennessey are expected to return to team training in October.