Fly-half Stephen Jones is almost certain to lose his fitness race to face South Africa in their opening World Cup game on Sunday.
The British and Irish Lion sat out Wales' August warm-up games with a calf injury and BBC Sport Wales understands it has still not fully healed.
Wales' other options at fly-half are James Hook and Jones' Scarlets team-mate Rhys Priestland.
"It's been unfortunate for Steve what's happened," said Priestland.
"But James Hook is one of our best players and some of the stuff he can do, you just look at him in training and you've just got to stick your hands up and say that's something special.
"I don't know what the coaches are going to do about selection, so all I can do is do my best in training and see what they think.
"Training has been really intense all summer, everyone has pushed each other for places which has been really good.
"As a squad we've really developed over the last few months."
Jones is currently tied on 100 Wales games with former team-mate Gareth Thomas as Wales' most-capped player and his wealth of experience could prove crucial during the World Cup.
But former Wales captains Jonathan Davies and Robert Jones believe that even if Jones had been declared fit ahead of Sunday's encounter in Wellington, his recent lack of match practice should rule him out.
Wales have other injury concerns over back row Ryan Jones, who has also struggled with a calf problem.
Prop Gethin Jenkins has already been declared unavailable for the opener as he continues to battle back following toe surgery in January and a calf injury that prevented him from playing in the August games against England and Argentina.
In Jenkins' absence Paul James has started all nine Wales games this year at loose-head prop and is likely to continue against the World Cup holders.
Wales coach Warren Gatland named Jenkins in his 30-man squad, even though the 30-year-old loose-head has had injury problems since January.
However, Gatland is confident the trio of calf-injury sufferers will be available for the game against Samoa on 18 September.
"They're progressing well and hopefully they're going to be fit for selection, if not for this game then definitely for the second game," said Gatland.
Ryan Jones rested his calf when Wales beat Argentina 28-13 at the Millennium Stadium last month.
Wales also suffered a spate of injuries to players in the build-up to the World Cup, which kicks off on 9 September when hosts New Zealand take on Tonga in Auckland.
Morgan Stoddart was ruled out with a broken leg, centre Gavin Henson suffered a wrist injury in a warm-up game against England in Cardiff and front row Matthew Rees followed medical advice to have surgery on his neck.
South Africa have had their own injury problems, with World Cup-winning flanker Juan Smith out of the tournament with an Achilles problem while lock Bakkies Botha is a doubt to face Wales with his own Achilles problem.
Both Gatland and opposite number Peter de Villiers will name their teams on Friday, with the Wales team being announced at 0200 BST.
