Wales will unleash a player with "a bit of x-factor about him" when Tomos Williams makes his Six Nations debut against France on Friday, according to Warren Gatland.

The Cardiff Blues scrum-half, who featured in six Tests last year, has been preferred to a more experienced Gareth Davies for the tournament opener in Paris.

And Wales head coach Gatland has no doubt about the 24-year-old's qualities.

"He is not the biggest man in the world, but he's competitive," Gatland said. "We feel he is a player with a future.

"He has things to work on – he knows that, from a defensive point of view – but he's got some lovely little touches and a bit of x-factor about him as well."

Davies has recovered from a thigh strain and is on the replacements' bench, and Gatland has announced two other starting XV changes following victory over South Africa in November, with Scarlets prop Rob Evans and Blues flanker Josh Navidi both gaining call-ups.

Evans takes over from Nicky Smith and Navidi returns after missing this season's entire autumn series because of injury.

Elsewhere, number eight Ross Moriarty makes a first appearance since mid-December after being sidelined because of concussion.

And Scarlets hooker Ken Owens will become his country's most capped player in that position, making a 61st appearance and overtaking Matthew Rees' record.

Victory for Wales at Stade de France would extend their unbeaten run to 10 games, matching a longest winning sequence since 1999.

But Gatland is wary of Les Bleus' threat, with his opposite number Jacques Brunel fielding a juggernaut pack – it has a combined weight of just over 150 stones – and a back division that includes 19-year-old debutant Romain Ntamack.

Ntamack makes an international bow against Wales – as his father Emile did 25 years ago – with defensive linchpin Mathieu Bastareaud surprisingly left out of the matchday 23.

Gatland added: "We had expected him (Bastareaud) to be included. He has been a big part of their squad.

"Probably what surprised me as much as anything was the fact he is not in the 23. I thought if he wasn't in the starting XV, he would be on the bench as an impact player for the last 20 minutes.

"Their last (home) game in the Six Nations was a win against England, and they should have beaten Ireland in that first game as well. They are going to be a tough proposition.

"It looks to me like they've got a big, bruising forward pack and a back-line with flair, talent and footwork.

"The game is about getting over the gain-line and getting front-foot ball, so we will probably use that.

"We will use our wingers or midfield. They will probably use their forward pack. It's an exciting challenge.

"We are coming under a bit of pressure. They clearly want to be big and physical up-front, and play some rugby when they get out wide."

Gatland, meanwhile, reiterated his view when asked for his thoughts about any possible future promotion and relegation in the Six Nations.

"I've said it before when I've answered this question. It would be healthy for the bottom (Six Nations) team to play the top team of the other European rugby championship," he said.

"But the team coming up has to be better than the team going down when you only have six teams in the competition.

"Georgia have been pretty successful. If Georgia went to Rome and beat Italy after they (Italy) finished last, then they probably deserve to go up."