Luscombe holds his rib as he comes off in his last game for the Dragons

Luscombe suffered the injury in Friday's Heineken Cup play-off defeat to Overmach Parma, and will be replaced by versatile Cardiff back Nick Macleod.

Macleod, 23, has been called back from a holiday in France and will fly out to Argentina on Sunday.

"Nick is another youngster who will learn from the experience of a tough tour," said Wales coach Gareth Jenkins.

"He gives us options and can play at outside-half and full-back as well as kick goals, and we are sure he will relish what is probably an unexpected opportunity for him.

"It's hugely disappointing for Hal to miss out in this manner and disappointing for the squad as he is one of our senior players.

"He has an impact injury which would have ruled him out of the first Test and should really take three to four weeks to fully heal.

"But, as with all such cases, we have to take a positive view of the situation and see the opportunity that has been created for others within the squad."

Luscombe was playing his last game for the Dragons by special permission ahead of a move to Harlequins, and only started after a last-minute deal to arrange insurance cover.

He went off in injury time after a big tackle from Robert Barbieri damaged his rib cartilage.

"It's so upsetting, absolutely devasting," he said after the game, in reference to both the injury and the result.

Fellow Wales tourists Nathan Brew, Luke Charteris, Ian Gough and Jamie Ringer came through the game unscathed, although tight-head prop Rhys Thomas aggravated a hip injury and left the field after 49 minutes.

I've got to use the tour as a stepping stone to making the World Cup squad Rhys Thomas

Thomas, born and raised in South Africa, hopes his injury will not affect his chances of making a first mark on the international scene.

"If I can show what I can do in Argentina, it will settle the question marks over my scrummaging," said the uncapped 23-year-old.

"People say those question marks are there, it's a reputation I've had, but that's in the past and my scrummaging has been pretty strong this season.

"I want to put all that to bed, which I can do if I show myself against the sort of power the Argentineans have.

"Now I've got a chance, it's a big opportunity and I've got to take it.

"I've got to get my foot in the door and use the tour as a stepping stone to making the World Cup squad next year."

Argentina will be without flanker Lucas Ostiglia (shoulder) for the series, while fly-half Felipe Contepomi misses the first Test on 11 June because of medical exams.

The Pumas' French-based stars involved in the French championship final (Biarritz v Toulouse) will also miss that game, but the full-strength squad should be available for the second Test on 17 June.

Full Argentina squad: R Alvarez Kairelis (Perpignan), M Ayerza (Club Newman), L Borges (Stade Francais), R Carballo (Toulon), M Carizza (Biarritz), F Contepomi (Leinster), I Corleto (Stade), M Durand (Montpellier), I Fernandez Lobbe (Sale), JM Fernandez Lobbe (Liceo Naval), N Fernandez Miranda (Hindu Club), P Gambarini (CASI), O Hasan (Toulouse), JM Hernandez (Stade), M Ledesma (Clermont), JM Leguizamon (L Irish), F Leonelli (Edinburgh), G Longo Elia (Clermont), FM Aramburu (Biarritz), JM Nunez Piossek (Bayonne), M Schusterman (Plymouth Albion), A Pichot (Stade), R Roncero (Stade), M Scelzo (Clermont), G Tiesi (L Irish), F Todeschini (Beziers).