Wales caretaker coach Rob Howley has named four uncapped players in a 38-man training squad to prepare for next month's clash against the Barbarians and three-Test Australia tour.
The group will officially assemble on May 21 with the exception of a sizeable Ospreys contingent that will be preparing for the RaboDirect PRO12 final against Leinster five days later.
Scarlets full-back Liam Williams, his team-mate prop Rhodri Jones, Ospreys centre Ashley Beck and Cardiff Blues wing Harry Robinson are the Test rookies involved.
Six players, meanwhile, have been called up from outside Wales' title and Grand Slam-winning squad this season, including flanker Martyn Williams, who is set to win his 100th cap against the Barbarians in Cardiff on June 2.
"The Ospreys will have our full backing in their bid for silverware in a fortnight's time, so we will not be asking them to join us until a week after everyone else," Howley said.
"They are playing very well at the moment, and a win in the final would be a great starting point for our own campaign this summer. The call-ups for both Dan Biggar and Andrew Bishop, in particular, reflect the good form the Ospreys are in.
"Elsewhere, we have been pretty consistent with selection. It's now down to these players to pick up where we left off in the Six Nations to prove to us that they should be on that plane to Australia.
"We hope to get the summer off to a winning start against the Baa-Baas, and everyone who figures in that game will be playing for a place on the tour."
France-based Mike Phillips and James Hook will be with the squad from the start of its preparations, while skipper Sam Warburton remains firmly on course to recover in time from a shoulder injury.
"Both Mike Phillips and James Hook will be with us from the start; Sam Warburton is still on track, and we are optimistic that both Jonathan Davies and Scott Williams will have reached full fitness and be able to play their part in the tour," Howley added.
"We have a tough series ahead of us with five matches in four weeks, but we are fully focussed on the prize of that elusive southern hemisphere scalp."
Clermont Auvergne full-back Lee Byrne is not selected as he is still likely to be involved in domestic competition in France up to the date the tour party leaves, but he will remain on stand-by.
Two players are unavailable for the tour due to injury - Cardiff Blues centre Jamie Roberts and Ospreys hooker Huw Bennett.
And there is, as expected, no place for controversial former Cardiff Blues back Gavin Henson.
Wales' 38-man training squad for Barbarians game on June 2 and Australia tour:
Backs: A Beck (Ospreys), D Biggar (Ospreys), A Bishop (Ospreys), A Brew (Newport Gwent Dragons), A Cuthbert (Cardiff Blues), J Davies (Scarlets), L Halfpenny (Cardiff Blues), W Harries (Newport Gwent Dragons), J Hook (Perpignan), G North (Scarlets), M Phillips (Bayonne), R Priestland (Scarlets), H Robinson (Cardiff Blues), R Webb (Ospreys), Lloyd Williams (Cardiff Blues), S Williams (Scarlets), Liam Williams (Scarlets).
Forwards: R Bevington (Ospreys), L Charteris (Newport Gwent Dragons), B Davies (Cardiff Blues), I Evans (Ospreys), T Faletau (Newport Gwent Dragons), R Gill (Saracens), R Hibbard (Ospreys), P James (Ospreys), G Jenkins (Cardiff Blues), A Jones (Ospreys), A-W Jones (Ospreys), Rhodri Jones (Scarlets), Ryan Jones (Ospreys), D Lydiate (Newport Gwent Dragons), K Owens (Scarlets), M Rees (Scarlets), A Shingler (Scarlets), J Tipuric (Ospreys), J Turnbull (Scarlets), S Warburton (Cardiff Blues, capt), M Williams (Cardiff Blues).