The Stade Francais-based star, who will return to Wasps next season, has been omitted from the matchday 22 completely after Courtney Lawes proved his fitness during training.
Lawes had been sidelined with a knee injury at the start of the tournament but interim England coach Stuart Lancaster looks set to name him on the bench for the Round 3 encounter, with Parling joining Mouritz Botha in the starting line up.
Former Newcastle second row Parling impressed as a replacement in Edinburgh and Rome, as did Northampton scrum-half Lee Dickson and Scarlets No8 Ben Morgan.
All three are expected to be promoted for the Welsh game, with Ben Youngs and Phil Dowson joining Palmer in missing out. Youngs and Dowson should feature in the 22, though, as will Toby Flood and Manu Tuilagi.
The high-profile Leicester duo haven't featured for England under Lancaster due to injury problems but have both now returned to action with their clubs. Lancaster will resist calls to draft the fly-half and centre into his first XV, with Charlie Hodgson and Brad Barritt likely to be retained and Flood and Tuilagi providing a potentially game-changing impact from the bench.
"We've had a great two days of training and some difficult selection decisions with players coming back into the equation," said Lancaster.
"There are some players who have missed out this time but their attitude in training has been outstanding.
"We will look forward to meeting again on Wednesday night with our match day 22 and finalising preparations for the game."
Harlequins full back Mike Brown, centre Jordan Turner-Hall and hooker Chris Brooker, Northampton flanker Calum Clark, Wasps scrum-half Joe Simpson and Leicester No8 Thomas Waldrom are the six other players to join Palmer in dropping out of the squad.