Rugby: All Blacks only team that should worry Wales - Former captain Sam Warburton

The Wales rugby team celebrates with their trophies after winning the Six Nations championship. Photo / AP

Former Wales captain Sam Warburton says the All Blacks are the only team he's wrorries about from a Welsh perspective at the Rugby World Cup.

"If somebody else beat New Zealand and knocked them out of the tournament, as a Welsh fan you would be thinking, 'Oh my God, this is on'," Warburton wrote in a column for the Sunday Times.

"Basically New Zealand are the only team I would really worry about Wales playing. If it was anyone else at the moment I would back Wales."

Warburton, who retired last season, heaped the praise on Wales coach Warren Gatland after his final Six Nations game in Cardiff.

"He has simply changed the psychology of the nation. He took over a nation of underachievers and now we expect to win the Six Nations every year. His first impact was on the players, obviously, but that has found its way all the way down to the fans."

Wales moved to number two in the latest World Rugby rankings following their Six Nations title clinching victory over Ireland yesterday.

With the 25-7 drubbing in Cardiff, Gatland's side won their 14th straight test match to leapfrog Ireland in the rankings. Wales were as low as eighth in the rankings less than two years ago after finishing fifth in the Six Nations.

It equals Wales' highest position in the world rankings which were introduced in 2003. Wales last reached second spot during the last Rugby World Cup after stunning England during the pool play.

The All Blacks remain in number one spot, a position they have held since November 2009.

England remain in fourth after a 38-38 draw with Scotland at Twickenham.

Victory earned Wales its first Six Nations title since 2013, and its first Grand Slam since 2012. After seeing his wet-weather game plan executed brilliantly, coach Warren Gatland deflected all praise to his players and staff.

"They deserve it. This group of players will run through a brick wall for you," he said. "I get such a buzz out of watching those guys go up and collect trophies and celebrate."

Gatland finished his 10th and last Six Nations with Wales by winning a fourth championship, and as the first coach to win three Grand Slams in the tournament's 136-year history. He's stepping down after the Rugby World Cup later this year, when he hopes to collect the biggest trophy yet.

"We're in a good position," he said.