England have named Gloucester number eight Luke Narraway as skipper for the non-cap game against the Barbarians at Twickenham on Sunday.
However, coach Stuart Lancaster has delayed naming his team because of a number of injury concerns.
One of them is Northampton scrum-half Lee Dickson, who has been ruled out of the game and the forthcoming Churchill Cup, as he requires shoulder surgery.
"Another 24 hours will give us time to finalise the squad," said Lancaster.
"We've got a couple of other injuries to assess and we'll have a look at some potential replacements in training today against the England Under-20 side."
Narraway has not started for England since the summer tour to New Zealand in 2008 with his last appearance for his country coming as a substitute against Ireland in the 2009 Six Nations.
The 27-year-old may have fallen out of England reckoning but he has been in resurgent form for Gloucester this season.
"We're pleased to announce that Luke Narraway will captain the side, which is a great reflection of the form and leadership qualities he's demonstrated at Gloucester this season," said Lancaster, the England Saxons head coach who is taking charge of this match.
England's squad includes several uncapped players including Exeter flanker Tom Johnson, Joe Marler (Harlequins), Kieran Brookes (Newcastle) and Gloucester centre Henry Trinder.
There are eight players from European finalists Northampton and from Quins.
Prop Marler, along with hooker Joe Gray, full-back Mike Brown and Lions wing Ugo Monye, helped Harlequins to victory in the European Challenge Cup final against Stade Francais in Cardiff on Friday, while fly-half Rory Clegg - also included in the England squad - was an unused replacement.
Marler, 20, who spent much of the 2009-10 season on loan at Esher in National League One, has enjoyed a breakthrough year with Quins, and made his debut for the second-string England Saxons in their win against Italy A in January this year.
Despite his elevation for the Barbarians encounter, Marler does not believe he is a candidate for the extended World Cup squad.
"If I was named in it, it would be a great honour, but I am not expecting anything big," he told BBC Sport.
"If I am in the Saxons squad, then great. It is a great opportunity to work with new people in a higher environment, the sort of stepping stone I am aiming for.
"In terms of my own standards and where I am at, I don't think I am anywhere near the first [senior] England squad.
"For me, this year was about setting a standard, going for it and trying to enjoy it a bit more. I didn't want to take it too seriously, because the pressure is only going to get more and more with every season.
"At the end of the day it is about enjoying it, and I have thoroughly enjoyed it.
"It has been a great experience and I have learnt a lot coming up against props like Carlos Nieto [Saracens], Martin Castrogiovanni and Dan Cole [both Leicester]."
No players from Leicester or Saracens were considered because of next Saturday's Premiership final between the clubs at Twickenham.
England will shortly name a 50-man squad for World Cup training ahead of three warm-up Tests in August, while the Saxons have matches against the USA on 4 June and Tonga on 11 June in the Churchill Cup before the final on 18 June.
Andrew Sheridan and Alex Corbisiero, who made his full debut in this year's Six Nations, are in pole position for the two loose-head roles in England's World Cup squad, but should anything happen to either, the competition is wide open.
England squad to face the Barbarians
Forwards: Dave Attwood (Gloucester), Kieran Brookes (Newcastle), Calum Clark (Northampton), Paul Doran-Jones (Gloucester), Carl Fearns (Sale), James Gaskell (Sale), Joe Gray (Harlequins), Tom Johnson (Exeter), Graham Kitchener (Worcester), Joe Marler (Harlequins), Matthew Mullan (Worcester), Luke Narraway (Gloucester), David Paice (London Irish)
Backs: Matt Banahan (Bath), Mike Brown (Harlequins), Rory Clegg (Harlequins), Paul Hodgson (London Irish), Charlie Hodgson (Sale), Ugo Monye (Harlequins), Stephen Myler (Northampton), James Simpson-Daniel (Gloucester), Henry Trinder (Gloucester), Jordan Turner-Hall (Harlequins)