England's Ollie Chessum will miss his side's final Six Nations fixture against title-chasing Ireland on Saturday due to an ankle injury.
Chessum suffered the problem in training on Tuesday and has been ruled out of the clash at Dublin's Aviva Stadium.
The 22-year-old, capped nine times, has overshadowed more established second-row partner Maro Itoje throughout the tournament.
But his breakthrough campaign is over, dealing a blow to England, who will now choose between David Ribbans, Nick Isiekwe, George Martin and Jonny Hill for his replacement.
"Ollie will be a huge loss. He's been great for us. We've played him in the second row but he covers back row for us as well," England defence coach Kevin Sinfield said on Tuesday.
Chessum is the second starter from Saturday's record-breaking 53-10 defeat by France to miss out against Ireland, the world's No 1 ranked team, after centre Ollie Lawrence was struck down by hamstring damage.
Manu Tuilagi has completed a three-week suspension for dangerous play and offers a direct replacement for the hard-running Lawrence, but Steve Borthwick may instead overhaul the midfield completely.
For the first time in this Six Nations, Borthwick will approach Thursday's team announcement with three fly-halves in contention after Marcus Smith, Owen Farrell and George Ford were retained in a reduced 30-man squad.
"It's about getting the balance right between giving those guys another shot but also making sure that the selection is right for the opposition we're playing against, which is what we've tried to do during the campaign," Sinfield said.
"We've tried to pick a team that suits both how we want to play but also the opposition's strengths and weaknesses."
Steve Borthwick has retained a 30-player squad for our match against Ireland this weekend ??@o2 | #IREvENG | #WearTheRose pic.twitter.com/wM7ji0uulf
— England Rugby (@EnglandRugby) March 14, 2023