Vunipola pushing for squad spot
Uncapped Wasps number eight Billy Vunipola could join his elder brother, Mako, in the England squad for Sunday's game against Ireland.
Vunipola is competing with Leicester number eight Thomas Waldrom for a place in the match-day squad after Ben Morgan was all-but ruled out of the Aviva Stadium clash through injury.
England coach Stuart Lancaster, meanwhile, has kept his midfield options open by including Manu Tuilagi, Brad Barritt and Billy Twelvetrees in the 25-man travelling squad.
Tuilagi is fit again after missing England's Calcutta Cup victory over Scotland and Lancaster must decide whether to bring the powerful Leicester centre straight back into the starting line-up.
Lancaster will name the team on Friday morning.
Morgan suffered a sprained ankle in the Scotland game and, although not officially ruled out by England, a team spokesman said he was "unlikely to figure" in Dublin.
James Haskell is expected to be promoted into the starting line-up at blindside flanker, with Tom Wood set to shift across the back row to replace Morgan at number eight.
That would leave a back row place vacant on the bench and the England management hold Vunipola in high regard following his explosion onto the scene in the Aviva Premiership this season.
Waldrom has more experience and Lancaster has gone on record as saying he was unfortunate to be dropped from the team after the defeat to Australia in the summer.
But England would also have no qualms about throwing 21-year-old Vunipola into a Test match, especially if it was off the bench, knowing the kind of impact his powerful carrying could make.
Lancaster's midfield decision is possibly the toughest selection poser of his reign.
England are a demonstrably more potent attacking force with Tuilagi in the side and his partnership with Barritt was central to the record victory over New Zealand last December.
Twelvetrees, though, enjoyed an eye-catching debut against Scotland when he came into the team at inside centre with Barritt shifting out of his natural position into the 13 jersey.
That led to immediate calls for Tuilagi and Twelvetrees to start together, an attack-minded choice that would sacrifice Barritt's key contribution as the team's defensive leader.
England could be reluctant to omit those key qualities against an Irish attack that includes the bewitching skills of Brian O'Driscoll and Jonathan Sexton.
Lancaster has today's training session to finalise his selection before announcing his team on Friday. The squad have Thursday off.