Billy Vunipola has been ruled out of England's autumn international against Australia with concussion and replaced by Thomas Waldrom of Exeter Chiefs.Back-rower Vunipola, 22, was dropped by coach Stuart Lancaster for England's 28-9 win over Samoa last Saturday, with Ben Morgan starting at number eight.
Vunipola was then injured in Saracens' 31-24 loss to Northampton and not included in England's 34-man pool.
Northampton fly-half Stephen Myler returns after recovering from injury.
12-6 win over Ireland in Dublin in the 2013 Six Nations, but has impressed for Exeter this season with seven tries in eight Premiership matches.
Myler, who kicked 16 points for Northampton in the victory over Saracens, has regained his berth in the squad for England's final November international following a hamstring strain.
Billy Twelvetrees looks in line for a starting berth against Michael Cheika's side at Twickenham on Saturday following words of praise from Lancaster, who has again released Bath's Kyle Eastmond from the squad.
Twelvetrees, 26, was England's first choice at inside centre for the 6 Nations earlier this year, but was dropped from the match-day squad for the November internationals against New Zealand and South Africa.
Lancaster handed the number 12 shirt to Eastmond, 25, for the Tests against the All Blacks and the Springboks, but says Gloucester skipper Twelvetrees has forced his way back into contention after impressing from the replacements' bench against Samoa.
"Billy Twelvetrees has responded well to the feedback I have given him. He did well from the bench and has put himself right back in the mix," Lancaster told SPORTMASTA live.
"We gave Kyle a chance from the start but Billy's chance could be just around the corner."
Eastmond's Bath team-mate Semesa Rokoduguni and Harlequins' Danny Care have also been released from the England training camp to give them additional training time ahead of Friday's Aviva Premiership match between the sides at the Recreation Ground.
Courtney Lawes has remained with the squad despite picking up a knee injury against Samoa and the Northampton lock will undergo treatment in the next few days to determine his availability.
England squadForwards: Joe Marler (Harlequins), Matt Mullan (Wasps), Kieran Brookes (Newcastle Falcons), David Wilson (Bath), Dylan Hartley (Northampton), Rob Webber (Bath), Dave Attwood (Bath), Graham Kitchener (Leicester), George Kruis (Saracens), Courtney Lawes (Northampton), Calum Clark (Northampton), James Haskell (Wasps), Ben Morgan (Gloucester), Chris Robshaw (Harlequins, captain), Thomas Waldrom (Exeter), Tom Wood (Northampton).
Backs: Lee Dickson (Northampton), Richard Wigglesworth (Saracens), Ben Youngs (Leicester), Brad Barritt (Saracens), Luther Burrell (Northampton), Owen Farrell (Saracens), George Ford (Bath), Stephen Myler (Northampton), Billy Twelvetrees (Gloucester), Mike Brown (Harlequins), Alex Goode (Saracens), Jonny May (Gloucester), Jack Nowell (Exeter), Anthony Watson (Bath), Marland Yarde (Harlequins).