Easter (pictured) impressed in England's victory over France last Saturday but has residual pain and restricted movement in his neck.
Joe Worsley moves from flanker to number eight with his Wasps team-mate Haskell making his debut at blindside.
The 21-year-old Haskell joins another club team-mate Tom Rees on the flank, making it an all-Wasps back row.
"It's been an odd week. I've been at Wasps and with England, I've trained at number eight and at six and was never sure how Nick was going to be," said Haskell.
"So to find out that I was actually starting was very exciting. It has been a pretty rapid ascent I suppose but I've always tried to approach each game one at a time, whether it's Wasps one week and Sevens the next, and learn from each performance and each area as I go.
"I learnt a lot from Sevens last year and playing for Saxons was a step up again. I just concentrate on my game and keeping my head down and let others worry about the big decisions. I just want to go out and perform.
"Joe Worsley and Tom Rees are great players. I enjoy playing with them at Wasps and hopefully we can take that forward against Wales."
The 6' 3" Haskell has represented England at U/18, U/19 and U/21 levels, as well as playing for the England Saxons and England Sevens teams.
In addition to Easter, England coach Brian Ashton is also without centre Mike Tindall from the team that played against France.
Matthew Tait comes off the bench to replace Tindall, while Mark Cueto has been recalled at full-back in place of out-of-form Josh Lewsey.
England: Mark Cueto (Sale); David Strettle (Harlequins), Mathew Tait (Newcastle), Mike Catt (London Irish, capt), Jason Robinson (Sale); Toby Flood (Newcastle), Harry Ellis (Leicester); Tim Payne (Wasps), George Chuter (Leicester), Julian White (Leicester), Martin Corry (Leicester), Tom Palmer (Wasps), James Haskell (Wasps), Tom Rees (Wasps), Joe Worsley (Wasps).
Replacements: Lee Mears (Bath), Stuart Turner (Sale), Louis Deacon (Leicester), Magnus Lund (Sale), Shaun Perry (Bristol), Shane Geraghty (London Irish), Jamie Noon (Newcastle).