LONDON, Aug. 18 (Xinhua) -- Wales has become the world's top-ranked Rugby Union side following their 13-6 win over England in Cardiff on Sunday.

The Welsh rise to first place comes off the back of an excellent run of form over the past year including a Six Nations Grand Slam earlier this year, and has coincided with the indifferent form of New Zealand, who had been ranked world number one for an unbroken decade.

Their new position at the summit of the rankings comes just 34 days before the Rugby World Cup kicks off in Japan.

The 13-6 win over England in Cardiff follows a 33-19 defeat in the reverse fixture seven days previously. However, despite that loss, Wales only required victory at the final whistle on Saturday to move to the top of the rankings.

"It's just a number, isn't it," head coach Warren Gatland told reporters. "It is a nice accolade to have, but it is all about the next few months and backing that up by performing well in the World Cup, and we've a couple of games against Ireland to go as well.

"It's nice for a day, but we won't be shouting from the rooftops about it. We have got to keep things in perspective.

"It's just a number. We are not making a big fuss of it. We will keep it in our pocket and go from week to week."

Wales will now head into the World Cup as one of the favorites to win the title alongside rivals England, former world number one side New Zealand, as well as Ireland, South Africa, Australia, and France.