London - England reserve hooker Jamie George has been ruled out of this weekend's Six Nations international against Wales at Twickenham with a potentially season-ending bicep injury, forwards coach Steve Borthwick said on Wednesday.
George's place on the bench at Twickenham on Saturday for what looms as a potential title showdown between the only two as yet unbeaten teams in this season's Championship will be taken by Luke Cowan-Dickie.
Saracens front-row George, who has made several notable impacts off the bench this Six Nations when replacing England captain and first-choice hooker Dylan Hartley, ruptured a tendon during training on Tuesday.
Exeter's Cowan-Dickie made his lone previous Test appearance against France in a warm-up match ahead of last year's World Cup.
George has been one of England's most promising players under new coach Eddie Jones but Borthwick said that as well as missing the Wales match, the hooker may struggle to play again this season after a scan indicated he could be sidelined for up to 10 weeks.
"Jamie hurt his biceps in training and had a scan. It's a ruptured tendon and it looks like he'll be out for eight to 10 weeks," Borthwick said.
"On the video of the training session, I watched the incident and it looked very innocuous. It was an arm out during a tackle and that was it," the former England captain added.
"He (George) carried on training and didn't think much of it, but then realised it was worse than he thought and saw the doctor."
Given George's injury, England will now expect even more of a lead from Hartley, but Borthwick said the 22-year-old Cowan-Dickie would not let anyone down if required off the bench.
"I watched Luke play for Exeter and since he's come into camp he's been very impressive. I've got to know him well and he's done well," Borthwick said.
"He's a really tough, physical player. He's a very strong ball carrier and is very competitive. He's done really well in training.
"There are no concerns over his inexperience coming into a game like this. These are all big games. Every England match is important."
Meanwhile Borthwick said lock Joe Launchbury had taken a full part in Tuesday's training session as he continues his return from the hamstring injury that forced him to miss England's 21-10 victory over Ireland.
England, the only team to have won all three of their matches this Six Nations, are due to name their team on Thursday amid speculation Launchbury will replace rising star Maro Itoje on the bench.
Wales, who drew their opening match against defending champions Ireland, named an unchanged side on Tuesday as coach Warren Gatland kept faith with the same XV that started the 19-10 home win over France on February 26.