Warren Gatland believes that Wales' Guinness Six Nations opener against France is potentially their toughest assignment of this season's tournament.

Wales tackle Les Bleus in Paris on February 1 during a campaign that also sees them meet reigning Six Nations champions Ireland and Eddie Jones' England at the Principality Stadium.

And head coach Gatland is upbeat about his team's prospects following a first clean sweep of autumn Test wins that stretched Wales' unbeaten record to nine games.

"I think we've got a great chance of winning the Six Nations, if we win that opening game," Gatland said, after naming a 39-man squad.

"That first game is going to be our toughest. We feel like we are in as good a position as anybody to do well.

"The whole thing about the Six Nations is momentum. If you can win your first couple of games, then you have a great chance of being in contention on the last weekend.

"This is competition time. The autumn was great, but it wasn't about points.

"This is what we are going to experience in Japan (World Cup), so it's about fronting up and winning games, playing some good rugby, but also thinking about tournament rugby."

Wales have suffered a major blow, though, after Bath number eight Taulupe Faletau broke his arm for the second time this season.

Faletau is not among Gatland's squad. He confirmed that he had originally selected a 40-player group, which included Faletau, before injury ruled him out.

Faletau returned to action for his club Bath against Heineken Champions Cup opponents Wasps on Saturday after 13 weeks out, only to break his right arm again.

Scarlets star Leigh Halfpenny, meanwhile, is involved. He has not played since suffering concussion during Wales' victory over Australia on November 10.

Gatland added: "We will make an assessment when he (Halfpenny) comes in. We will see where he is at.

"He has been advised to continue training and stuff. If he's right, he will be in contention, but if not, we will have to make some other plans.

"Seven or eight players are carrying knocks at the moment and may be available for the second match (against Italy). We will monitor these guys over the next few weeks, and hopefully they may be in contention for the first game, if not the second game."

The Wales squad will report for duty next Monday, with players on the assessment list set to include Dan Biggar (knee), Rhys Patchell (hamstring), Adam Beard (neck) and Ross Moriarty (concussion).

"Biggar's hopefully going to be okay," Gatland said. "That's why we've gone for the four 10s, with Rhys Patchell not being 100 per cent.

"We wanted to have two fit 10s for training in Gareth Anscombe and Jarrod Evans. Dan has a medial injury, but he is a fast healer."

Gatland's Six Nations group includes Wasps flanker Thomas Young and Leicester back Jonah Holmes.

Young, who won caps against Tonga and Samoa in 2017, has been among the Gallagher Premiership's form players this term.

Holmes made his Test debut earlier this season, and he has continued to shine for his club Leicester, despite the Tigers' inconsistent form.

Lock Alun Wyn Jones captains a squad that features many of Gatland's tried-and-tested players, including fit-again Cardiff Blues back-row forward Josh Navidi, who missed the autumn games through injury.

This season's tournament is Gatland's final Six Nations as Wales boss. He steps down after the World Cup later this year, bringing a 12-year tenure to an end.