Great Britain have released four players from their squad ahead of their opening Tri-Nations Test against New Zealand in Christchurch on Saturday.
Warrington duo Lee Briers and Ben Westwood, Salford's David Hodgson and Wigan's Mickey Higham will return home.
They were part of a stand-by squad which helped Britain beat a Newcastle team in a warm-up match on Friday.
Forward Paul Wood moves into the 25-man squad while wing Stuart Reardon stays with the group as emergency back-up.
The final squad has only one recognised full-back in Paul Wellens and just three specialist centres.
"Following our warm-up game, the staff have now finalised their plans for the series," said team manager Abi Ekoku.
"We would like thank the players returning home for their contributions to the squad and the professionalism they have shown during their time with the group," added Ekoku.
Briers, who won his solitary Great Britain cap against France in 2001, will now be free to captain Wales in their World Cup qualifier against Scotland in Bridgend next Sunday.
Westwood, Hodgson and Higham may be made available for England's games against Tonga and Samoa in the Federation Shield.
The Great Britain squad will remain in Sydney until Thursday when they fly to Christchurch for their 28 October fixture with the Kiwis.
Great Britain's revised 25-man squad: M Aspinwall (Huddersfield), R Burrow (Leeds), B Carney (Newcastle Knights), G Carvell (Hull), A Coley (Salford), G Ellis (Leeds), S Fielden (Wigan), L Gilmour (St Helens), M Gleeson (Warrington), G Hock (Wigan), R Horne (Hull), L Pryce (St Helens), S Long (St Helens), D McGuire (Leeds), A Morley (Sydney Roosters), T Newton (Bradford), S O'Loughlin (Wigan), J Peacock (Leeds, capt), G Raynor (Hull), J Roby (St Helens), K Senior (Leeds), P Wellens (St Helens), J Wilkin (St Helens), P Wood (Warrington), K Yeaman (Hull).