Cardiff - Wales top the world rugby rankings for the first time in their history but coach Warren Gatland was more pleased with the character they showed in the gritty 13-6 win over England on Saturday.

George North's converted try - his 38th for his country - was the difference between the sides with Wales replacing world champions New Zealand at the top of the rankings.

England looked a shadow of the side that beat Wales 33-19 at Twickenham last Sunday, their lack of punch in attack reflected by failing to score a point in the first-half for the first time since the 2011 World Cup match with France.

The All Blacks had held the spot for almost a decade - reaching the pinnacle in the standings in November 2009 -- and their 36-0 demolition of Australia earlier on Saturday suggests the Welsh stay may be a short one.

Gatland, who ends his 12-year tenure at the end of the World Cup, did not make too much of being number one.

"It's just a number, isn't it," he said.

"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.

"Lots of journalists will be out there saying 'this is a joke' -- probably Kiwi journalists more than anything! It's just a number."

His England counterpart Eddie Jones made a joke of it.

"They're favourites for the World Cup now. When you go to number one, you're favourites for the World Cup," said the Australian.

Gatland - who guided the Welsh to the 2011 semi-finals - said losing full-back Liam Williams in the warm-up to a tightened hamstring illustrated the resilience of his players.

"I said to the boys in the changing room, we showed massive character and big cojones (testicles)," said the 55-year-old New Zealander, who added Williams' withdrawal was more precautionary than anything else.

Gatland - who will take the squad to Turkey this week before a double header with Ireland - has lost two key players for the World Cup in back-row forward Taulupe Faletau and fly-half Gareth Anscombe.

However, he said he had been delighted by Dan Biggar's performance at fly-half and took aim at former Wales winger JJ Williams who said the Welsh would not win a World Cup with him as a starter.

"I thought he played well and we were positive in the way we wanted to play," said Gatland.

"I don't know about any former Welsh player (JJ Williams). Was he really old and played 50 odd years ago in the 1970s? That probably does explain a few things."

Biggar sparked the North try by taking a penalty very quickly - as England wing Anthony Watson was still going off the pitch to the sin bin - dispelling Williams's claim he lacks creativity.

"Special thanks to JJ Williams for his comments this week, it's been really motivating," said Biggar.

Jones did not wish to make much out of Pascal Gauzere allowing Biggar to take the penalty with Watson still on the pitch - England were effectively down to 13 men as scrum-half Willi Heinz was about to go off for a Head Injury Assessment (HIA).

"I should have studied my rugby league harder this week," said Jones, whose side face Ireland at Twickenham next Saturday.

"I'll go up to Wigan and get some lessons on how to defend with 13 men.

"We have to cope with it. It was a difficult situation, we didn't cope, so well done to Wales."