Warren Gatland believes it would be an "unbelievable" achievement for Wales to reach the Rugby World Cup final.

The Six Nations champions will contest the Webb Ellis Cup against England or New Zealand if they beat South Africa in Yokohama on Sunday.

Two previous World Cup semi-final appearances - in 1987 and 2011 - resulted in defeats at the hands of New Zealand and France, respectively.

But Wales have won 20 of their last 23 Tests, bringing an exciting conclusion to Gatland's success-laden coaching reign that started 12 years ago.

"I just think for us to get to the final of a World Cup, it will be unbelievable given the small playing numbers we have in Wales," head coach Gatland said.

"We feel like we continually punch above our weight.

"But the greatest thing about this group of players, since I have been involved with Wales, is when they put that red jersey on and play for Wales, how much that means.

"If we can make the World Cup final with the playing numbers we have got, it would be one hell of an achievement.

"It's one step at a time. We have got a challenge on our hands on Sunday against a side that has been improving.

"I am excited about it. I'm more looking forward to this game than I was last week (the quarter-final against France), and more confident about this game than we probably were against France.

"There are probably nine or 10 players who won't be involved in another World Cup as well, so they have got to relish that opportunity and be excited about this.

"You have got a chance to do something special in your life, and these chances come along very rarely and you have got to grab them with both hands.

"When you want something bad enough and you really, really want it, then it can happen."

Gatland will head home to New Zealand to coach Hamilton-based Super Rugby side the Chiefs next year before taking charge of the 2021 British and Irish Lions' South Africa tour.

"I have not looked that far ahead," he added. "I am not sure the WRU (Welsh Rugby Union) would let me take the World Cup back to New Zealand!

"They are things you have to dream about, and one of the things about me is that I am probably the greatest optimist in terms of believing something is possible and that there is a dream.

"If you don't have that attitude and portray it, it will not happen. A big part of success is the belief and the desire to do something.

"That is what we will be building on in the next two days, and I can go back to New Zealand with my head held high.

"The biggest thing I am proud of (with Wales) is that I think we have earned respect from the rest of the world in terms of what we have achieved in the last 12 years.

"The world rankings where we were at (10th), what we have achieved in terms of Six Nations and Grand Slams... I would love to beat the All Blacks, and that is one thing I have not achieved. Respect for what we have done is the biggest thing."

Wales have beaten South Africa five times in the last six meetings, although it has not prevented Wales from being written off in some quarters.

"If they continue to do that (write Wales off) over the next couple of days, that would be brilliant," Gatland said. "Please continue to do that, as it does get us up when people write us off.

"It will probably be a kicking fest (on Sunday), they (South Africa) kicked 30 times against Japan, so we just have got to be able to handle their game.

"It won't be the prettiest game in the world, it will be a tight Test match with probably teams playing for territory, depending on what the weather is like."