Wales captain Dan Biggar said on Wednesday he believes a testing tournament opener at Ireland will be central to his side's hopes of a successful defence of their Six Nations title.

Few pundits have backed an injury-hit Wales to finish top of the table this season despite the way in which they ended their November campaign with a thrilling 29-28 win over Australia.

Wales are set to be without a vastly experienced group of players -- Alun Wyn Jones, Ken Owens, Leigh Halfpenny, Justin Tipuric and Josh Navidi -- for the entire tournament.

Star winger George North and No 8 Taulupe Faletau are believed to have a slim chance of featuring in the latter stages.

It all makes an opening match against Ireland, who beat New Zealand 29-20 in November, in Dublin an even more daunting assignment than usual.

"It's a really tough start," said fly-half Biggar, skipper in place of Jones, at the Six Nations' virtual media launch.

"Obviously, with the form Ireland showed in the autumn -- how impressive they are -- and we know how tough going to Dublin is. We haven't had a huge amount of success there over the last few years."

'Momentum'

Biggar, who plays his club rugby in England for Northampton Saints, added: "This tournament, in particular, hinges on momentum, really.

"If you get off to a good start, then everything seems to flow, camps become a lot happier and training becomes a lot easier.

"If you can pick up an away win on the first weekend, then it sets you up really nicely. We have then got Scotland at home, which we know is going to be hugely difficult as well."

"We were written off last year," added Biggar, who has played 95 Tests for Wales.

"We are coming into the tournament as defending champions, so there is certainly a bit of a swagger in the group."

The 32-year-old said there was a potential benefit from the injury crisis a year ahead of the 2023 Rugby World Cup in France.

"From our point of view, there are lots of key experienced players missing, but that also gives an opportunity to a lot of young lads who have come into the squad to step up and really stake a claim," he said.

Jones, the most-capped player in the history of international rugby union, has undergone two shoulder operations since being injured against New Zealand in October.

The lock also had shoulder problems ahead of last year's British and Irish Lions' tour of South Africa yet still recovered to lead the invitational side in all three Tests.

"I don't think any of us expected him to turn up in South Africa in the summer, and he managed to get on the plane," said Biggar.

"If there is anybody who has got a chance of being fit for some part of this tournament, then Al is probably the man. I wouldn't rule it out just yet."