Ross Moriarty and Tomas Francis have been included in Wales' expanded 47-man training squad for the 2015 World Cup.
Gloucester back-row Moriarty and Exeter tight-head prop Francis are dual-qualified for Wales and England.
But Wales coach Warren Gatland has moved first to claim the uncapped pair.
Moriarty's Gloucester team-mates James Hook and Richard Hibbard are included, while Bristol fly-half Matthew Morgan is rewarded for his strong end-of-season performances.
Francis' Exeter team-mate Tom James - last capped in 2010 - is also an unexpected inclusion. The 28-year-old wing is set to rejoin Cardiff Blues next season.
Premiership Rugby has confirmed the English Premiership clubs will release players immediately for Wales' World Cup camps and warm-up matches - after coming to an agreement with World Rugby.
There had been concerns England-based Welsh players would miss training and warm-up games because of issues such as insurance.
The new agreement applies to all players called up by any nation for the 2015 World Cup.
"Premiership Rugby is pleased to confirm that we have come to an agreement with World Rugby to release all our players called up by any nation for the Rugby World Cup from this week," said a Premiership Rugby spokesperson.
"We are grateful to World Rugby for this co-operation in this matter as we had to ensure all our clubs and players are properly protected when players are released on international duty. "
"This variance to our policy to only release players within the confines of Regulation Nine will only be applied for the 2015 Rugby World Cup."
With centre Jonathan Davies ruled out of the World Cup by a serious knee injury, Tyler Morgan - withdrawn for the Wales Under-20 squad heading for the World Rugby U20 Championship - adds depth to the midfield options.
But there is no place for Ospreys centre Ben John or Cardiff Blues back-row Josh Navidi, although his Blues team-mates Rhys Patchell, Gareth Anscombe and Cory Allen do get the nod.
Moriarty, 21, has played for England Under-20s, but qualifies for Wales through his father - former dual code Welsh international Paul - while his uncle Richard is a former Wales captain.
England's official second team is the Saxons, so Moriarty is still eligible to play for Wales.
The uncapped pair of Bath lock Dominic Day and Wales Under-20s captain Rory Thornton are also included, although Osprey Thornton will link up with the squad after the U-20s Championship.
The squad will be trimmed to a final 31 at the end of August, following training camps in Switzerland, Qatar, Poland and north Wales, plus two warm-up games against Ireland.
"We are extremely happy with the blend of the squad in terms of the experience we are able to include as well as the young talent that has really impressed us," said Gatland.
"The easy part for the players has been done in terms of being selected, the hard work will begin from day one with a huge schedule of preparation ahead of them.
"The 47 players all have the opportunity to make that 31-man party and I'm sure they will all be eager to feature in a World Cup on these shores.
"We believe the longer we are together the better we perform and this summer of preparation will give us every opportunity to be at our best come the Rugby World Cup."
Wales will face hosts England, Australia and Fiji in Group A after an opening game against Uruguay on 20 September in Cardiff.
Wales training squad:
Backs: Gareth Davies (Scarlets), Mike Phillips (Racing Metro), Rhys Webb (Ospreys), Lloyd Williams (Cardiff Blues), Gareth Anscombe (Cardiff Blues), Dan Biggar (Ospreys), James Hook (Gloucester Rugby), Matthew Morgan (Bristol Rugby), Rhys Patchell (Cardiff Blues), Rhys Priestland (Scarlets), Cory Allen (Cardiff Blues), Jack Dixon (Newport Gwent Dragons), Tyler Morgan (Newport Gwent Dragons), Jamie Roberts (Racing Metro), Scott Williams (Scarlets), Hallam Amos (Newport Gwent Dragons), Alex Cuthbert (Cardiff Blues), Leigh Halfpenny (Toulon), Tom James (Exeter Chiefs), George North (Northampton Saints), Eli Walker (Ospreys), Liam Williams (Scarlets).
Forwards: Rob Evans (Scarlets), Tomas Francis (Exeter Chiefs), Paul James (Bath Rugby), Aaron Jarvis (Ospreys), Gethin Jenkins (Cardiff Blues), Rhodri Jones (Scarlets), Samson Lee (Scarlets), Nicky Smith (Ospreys), Scott Baldwin (Ospreys), Kristian Dacey (Cardiff Blues), Richard Hibbard (Gloucester Rugby), Ken Owens (Scarlets), Jake Ball (Scarlets), Luke Charteris (Racing Metro), Dominic Day (Bath Rugby), Bradley Davies (Wasps), Alun Wyn Jones (Ospreys), Rory Thornton (Ospreys), Dan Baker (Ospreys), Taulupe Faletau (Newport Gwent Dragons), James King (Ospreys), Dan Lydiate (Ospreys), Ross Moriarty (Gloucester Rugby), Justin Tipuric (Ospreys), Sam Warburton (Cardiff Blues, capt).