London - Gareth Anscombe says the impact of missing the Rugby World Cup will not hit home till the star flyhalf sees his Wales team-mates run out for their first pool match in Japan.

The 28-year-old New Zealand-born playmaker - who was man of the match when Wales overwhelmed Ireland 25-7 in March to win their third Six Nations Grand Slam under Warren Gatland - will miss the sport's quadrennial showpiece due to a knee injury he suffered in a warm-up match with England earlier this month.

Dan Biggar will step in to the starting XV whose first match at the World Cup is against Georgia on September 23 in Toyota City.

"I don't think it is fully going to hit until I wake up at eight in the morning to watch the boys run out in Japan," Anscombe told The Times in his first interview since his dreams were dashed.

Anscombe, who qualified for Wales through his Welsh mother, says his injury put paid to two years of careful planning by Gatland in how best to use him and Biggar during games.

"We spent a hell of a lot of time working towards this and particularly the last two years, what we've achieved has been pretty special," said Anscombe, who was first capped in 2015.

"It is disappointing for that journey to end so quickly. It wasn't meant to be for my journey.

"It's been pretty eventful, but I feel like I've been able to become a lot more comfortable in the group.

"That's the hardest thing. You spend all this time training -- I spent two weeks in Switzerland doing a lot of hard work -- and for it to be taken away so quickly, you want to get over to Japan and spend six weeks with the boys and hopefully there is a pretty big trophy at the end of it."

Anscombe, who said he felt "pretty numb" when the scan revealed the anterior cruciate ligament damage to his right knee and also an injury to his meniscus, said he was not sure teams required four warm-up games before the tournament itself.

"They are tough," he said.

"It's pretty rare that you go ten weeks without a game and then your first game is a game of international rugby.

"We need the games. Whether four is the magic number I don't know."

Anscombe, who revealed the surgeon took a graft from his hamstring - "that's my new ACL," he says nonchalantly -- believes Wales have a chance of winning their first World Cup and give the departing Gatland the ultimate leaving present.

"It's not the be-all and end-all but I do think it's really important that we can win the pool (the winners would play the runners-up in Pool C likely to be either England or France)," he said.

"If we beat Australia (September 29 in Tokyo), then it is a good, solid draw.

"We feel we can beat anyone. If we can get to the knockout stage, I really feel we are a tough team to beat.

"At a World Cup you just need a bit of luck. If we get a bit of luck, I think the team can go and do something special."