Warren Gatland admits that choosing the Wales back-row players he will take to the World Cup will be one of his hardest tasks.
The Wales coach names his 30-man squad on Monday with 10 back-row options battling for spots.
"It's a nice problem to have at the moment in terms of how the mix is going to be," said the New Zealander.
Gatland made his comments after his side's "creaky" performance in beating Argentina 28-13 in Cardiff on Saturday.
Try-scoring number eight Andy Powell impressed the coach, as did veteran openside Martyn Williams who led Wales on his 99th appearance and final game for Wales at the Millennium Stadium.
Sam Warburton, Toby Faletau, Danny Lydiate, Ryan Jones, Jonathan Thomas, Justin Tipuric, Josh Turnbull and Gareth Delve were also in Wales' preliminary tournament squad.
However, Melbourne Rebel Delve did not feature in any of Wales' warm-up games and Thomas and Turnbull did not start in any of them.
Also up front Cardiff Blues prop Scott Andrews and Scarlets hooker Ken Owens have been unused by Wales and released for pre-season regional duty while Delve has also featured for Melbourne Rebels, who are touring the British Isles.
Behind the scrum, all of the backs Gatland is considering have played except Stephen Jones, whose calf injury has prevented him from appearing.
"There were some nice touches from Andy Powell, Dan Lydiate maybe wasn't as prominent as he was in the first two games and we want to have a look at that," said the man who has been Wales' coach since 2008.
"And obviously there were some nice touches from Martyn Williams as well.
"It's a nice problem to have at the moment in terms of how the mix is going to be."
Gatland and his management will ponder the split between forwards and backs ahead of Monday's announcement.
The debate centres on whether Wales will take 17 forwards and 13 backs or 16 forwards and 14 backs.
"It's just deciding the mix on whether we go 17-13 or 16-14 split and I thought there were some players who really gave us some tempo and energy in the first two games," said Gatland.
"But that's easy against England as well because when you play against England you're pretty fired up as well and we probably didn't quite have the same sort of tempo today [against Argentina] at the start.
"But... there's nine changes [to face Argentina] and... it's sometimes a little bit harder to get up for Argentina than perhaps it is for England.
"So you've just got to take that in mind."
British and Irish Lions tight-head prop Adam Jones returned after a toe injury and Gatland says the Osprey can improve his overall performance.
"Adam Jones definitely needs a bit more rugby," said Gatland.
"His scrum was good, but obviously he needs to keep working hard and, again, I thought the bench gave us some momentum when they came on.
"The guys really added to the tempo, which has probably been the most pleasing aspect of the last three games."
Gatland was also encouraged by being able to overcome the Pumas while Wales were not at their best and was delighted with their second try, scored by Ospreys lock Jones.
"We took our opportunities," said Gatland. "I thought our second try was absolutely fantastic down the short side.
"George North showed some great footwork and composure and then Alun Wyn Jones, who I thought had a fantastic game and worked really, really hard... was rewarded for his effort."
Wales' preliminary World Cup squad
Forwards: Scott Andrews, Gethin Jenkins (Blues), Lloyd Burns (Dragons), Huw Bennett, Ryan Bevington, Richard Hibbard, Adam Jones, Paul James (Ospreys), Ken Owens, Craig Mitchell (Exeter), Bradley Davies, Sam Warburton, Martyn Williams (Blues), Luke Charteris, Danny Lydiate, Toby Faletau (Dragons), Ryan Jones, Alun Wyn Jones, Jonathan Thomas, Justin Tipuric (Ospreys), Josh Turnbull, (Scarlets), Gareth Delve (Melbourne Rebels), Andy Powell (Sale Sharks).
Backs: Michael Phillips (Bayonne), Lloyd Williams (Blues), Tavis Knoyle (Scarlets), Jamie Roberts (Blues), James Hook (Perpignan), Jonathan Davies, Stephen Jones, Rhys Priestland, Scott Williams (Scarlets), Leigh Halfpenny (Blues), Lee Byrne (Clermont Auvergne), Aled Brew (Dragons), Shane Williams (Ospreys), George North (Scarlets).