Hendre Fourie is on standby to start for England against Ireland - just five days after being omitted from Martin Johnson's World Cup squad.
The Sale flanker has joined up with England as emergency cover after number eight Nick Easter and flanker Tom Wood both suffered calf injuries.
Easter will undergo a fitness test on a tight calf on Saturday morning.
Northampton flanker Wood suffered what England manager Martin Johnson described as a "mild calf strain".
He will be replaced on the bench by Stade Francais lock Tom Palmer.
If Easter is ruled out Fourie will go into the team at open-side flanker, with James Haskell switching to number eight.
Haskell himself had been passed fit after suffering mild inflammation to a tendon in his foot.
With England's resources stretched, starting lock Courtney Lawes will be called upon to provide the back-row cover.
Prop Andrew Sheridan will return to the England side for Saturday's game after missing the opening two warm-ups following summer shoulder surgery.
England will test a new centre pairing of Mike Tindall and Manu Tuilagi, while Chris Ashton returns.
Jonny Wilkinson and Richard Wigglesworth form a new half-back combination and scrum-half Joe Simpson could make his debut off the bench.
Steve Thompson gets the nod over Dylan Hartley to continue at hooker alongside Sheridan and Dan Cole. Tom Croft returns at blind-side.
Tuilagi made a try-scoring debut against Wales on 6 August and returns to the team in place of Shontayne Hape, with Tindall moving to inside centre.
"We wanted to give Manu another game and Mike another game," said Johnson, who indicated he wanted to try different combinations in case they were required during the World Cup.
"We're in a good position where we have lots of tough decisions to make. Game time is precious. When you only have 30 players and don't have instant replacements on stand-by, you need to be a bit flexible, so it is not a bad thing to start now."
Asked whether Hape had been dropped after his ineffectual display in Cardiff, Johnson added: "He's not been picked, but neither has Dylan Hartley and 15 other players.
"We're picking the right team for this game and this opposition. Shontayne is a very consistent player for us. We value him. I've no qualms he'll perform."
Tindall, who continues as captain in the absence of Lewis Moody, will win his 72nd cap and draw level with Will Carling as England's most-capped centre.
There is a first start of the World Cup warm-up campaign for Ashton following a foot injury, and he joins Ben Foden and Mark Cueto in the back three.
Wilkinson reclaims the number 10 shirt from Toby Flood, a firm indication that Wilkinson is now likely to begin his fourth World Cup in the starting XV.
Wigglesworth, who limped off after half-an-hour in Cardiff, retains his place at scrum-half as Ben Youngs continues his recovery from a knee operation.
Sheridan requires a strong showing to prove he should start the World Cup opener against Argentina on 10 September.
"Andrew needs to play," Johnson acknowledged. "He has got a fair bit of experience in coming back from injury, but Alex [Corbisiero] has put pressure on that position and Matt Stevens can play there as well, so there is a lot of competition.
"There is no substitute for a tough game and that is why we are going to Dublin."
England team: Ben Foden (Northampton); Chris Ashton (Northampton), Manu Tuilagi (Leicester), Mike Tindall (Gloucester, captain), Mark Cueto (Sale); Jonny Wilkinson (Toulon), Richard Wigglesworth (Saracens); Andrew Sheridan (Sale), Steve Thompson (Wasps), Dan Cole (Leicester), Louis Deacon (Leicester), Courtney Lawes (Northampton), Tom Croft (Leicester), James Haskell (Ricoh Black Rams), Nick Easter (Harlequins)/Hendre Fourie (Sale.
Replacements: Dylan Hartley (Northampton), Matt Stevens (Saracens), Simon Shaw (Unattached), Joe Simpson (Wasps), Tom Palmer (Stade Francais), Delon Armitage (London Irish).