Mike Phillips and Dwayne Peel left out of Wales squad
Gatland concedes scrum-half worry
Scrum-halves Mike Phillips and Dwayne Peel have been left out of Wales' 35-man Six Nations squad - but both are in line to make swift returns.
Peel should be fit to face Scotland on 13 February with Phillips just behind.
Gareth Cooper is the experienced number nine in Wales' squad while Scarlets scrum-half Martin Roberts and uncapped Richie Rees win Six Nations calls.
Ospreys Kristian Phillips, 19, and Tom Prydie, 17, join Saracens prop Rhys Gill as Wales' other uncapped players.
Sale prop Eifion Lewis-Roberts and Ospreys lock Ian Gough are recalled.
British and Irish Lions star Phillips is coach Warren Gatland's first-choice scrum-half but the Ospreys player has been out since October after injuring his foot in a game against Clermont Auvergne.
Prop Rhys Gill has been a regular for high-flying Saracens this season
The 27-year-old, who played every minute of the three 2009 Lions Tests in South Africa, had hoped to be named in Gatland's initial squad.
Phillips' absence had meant Peel was favourite to start for Wales against England in their Six Nations opener at Twickenham on 6 February.
But Peel, 28, hobbled off in the 52nd minute of Sale Sharks' Heineken Cup defeat at the Cardiff Blues on Saturday with a groin strain.
Peel, who was hoping to add to his 72 Wales caps at Twickenham, underwent a scan by the Sharks medical team on Monday as they tried to find out the full extent of his problem.
A Sale spokesman said on Monday night: "Dwayne has had the scan results, he has a slight strain and will be out for three weeks."
Gatland said Wales would "assess him over the next few weeks" and stressed that both Peel and Phillips could be added to his Wales squad.
McBryde assesses Gill and Roberts
Ospreys coach Sean Holley hopes Phillips will return in their Magners League game with Connacht on 21 February and Gatland may call on the 27-year-old for Wales' game with France at the Millennium Stadium.
"Mike Phillips may return for possibly the third or fourth game," said Gatland.
"But he needs a few games under his belt as he has just started running.
"It is a position where we have a couple of key players that are injured.
"Gareth has been part of the squad but has not been selected as a first-choice for the Blues so it is a little bit of a concern for us."
Cooper, who has won 44 Wales caps, is now front-runner to start against England despite a lack of form for the Blues.
Fellow Blues scrum-half Rees has been rewarded for his good form - including his toe-to-toe battle with Wales rival Peel in Europe on Saturday - with a Wales call while Scarlets number nine Roberts is also named in Gatland's squad.
"Rees' service is pretty good, he is a threat around the fringes and he is pretty physical," said Gatland.
"Out of the two number nines of Saturday, Richie probably had the upper hand on Dwayne even though Dwayne had a little knock.
"We have been impressed with the way he has developed and his decision-making has improved."
Gatland's call up of rookie Ospreys wings Phillips and Prydie are the major shock as the teenagers have hardly figured for their region but have starred in Wales' semi-professional Principality Premiership with Neath and Swansea respectively.
Wales have issues on the wing as Mark Jones is sidelined by a knee injury while Leigh Halfpenny and Tom James are still considered raw alongside experienced Welsh record try-scorer Shane Williams.
The Ospreys star, who is 33 next month, has only recently returned from a hamstring tear and has only played two minutes of rugby since sustaining his injury in Wales' final autumn series defeat to Australia.
So Gatland has called up teenagers Phillips and Prydie, who has played just once for the Ospreys.
Phillips won December's Premiership Player of the Month award for his blistering form after scoring against Llandovery and Aberavon before a five-try rout against Pontypool.
Prydie, meanwhile, made Heineken Cup history when he made his European bow in December for the Liberty Stadium region aged just 17 in their win over Viadana.
Gatland hopes prop Gill can help their front row problems as the 23-year-old, released by the Blues in 2009, has played regularly for Saracens as they have moved to second in the Guinness Premiership.
Lions prop Adam Jones and Lions hooker Matthew Rees are to return for Wales while star full-back Lee Byrne is also a crucial player that comes back for Gatland.
"We are now at the beginning of our countdown to the world cup and this slightly larger squad reflects that," said Gatland.
"We have brought in some youngsters to put some pressure on some of our senior players and to help increase the depth we have in certain positions.
Archive - Five-star Kristian Phillips
"Kristian is a good example of an exciting young player, he has just won the Principality player of the month award and scored five tries in one match for Neath, he is skilful and very quick.
"Elsewhere we are very happy to welcome back the likes of Adam Jones and Lee Byrne who were both obviously missed in the Autumn, although at full-back in particular a certain James Hook provided more than ample cover.
"Our first match at Twickenham could set the tone for the Championship for both sides, we will both be desperate to win that first up match.
"We then come to the Millennium Stadium for two home matches and the support we have there will make a huge difference to us."
Rees and Scarlets team-mate Stephen Jones, the Lions fly-half, have missed their region's recent games but hope to return in their Heineken Cup pool clash in Brive on Saturday.
But Scarlets flanker Dafydd Jones' shoulder injury means he will join props Duncan Jones (foot) and John Yapp (bicep) and centre Gavin Henson (indefinite unpaid leave) on Wales' absent list.
Wales' 35-man Six Nations squad:
Backs: Gareth Cooper, Leigh Halfpenny, Tom James, Richard Rees, Jamie Roberts, Tom Shanklin (all Cardiff Blues) Dan Biggar, Andrew Bishop, Lee Byrne, James Hook, Kristian Phillips, Tom Prydie, Shane Williams (all Ospreys), Jonathan Davies, Stephen Jones, Martin Roberts (all Scarlets).
Forwards: Bradley Davies, Gethin Jenkins, Deiniol Jones, Andy Powell, Sam Warburton, Gareth Williams, Martyn Williams (all Cardiff Blues), Huw Bennett, Ian Gough, Paul James, Adam Jones, Alun-Wyn Jones, Ryan Jones, Jonathan Thomas (all Ospreys), Matthew Rees (Scarlets), Luke Charteris, Dan Lydiate (both Newport Gwent Dragons), Eifion Lewis-Roberts (Sale Sharks), Rhys Gill (Saracens).
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