England can beat anyone at this autumn's World Cup, according to former captain Will Carling.
But it was an opening-day 21-16 win in Wales that impressed Carling.
"England will learn that if they go out every game with the intensity they did against Wales, then they can beat anyone," Carling told Sportsweek.
The 49-year-old, who captained England to the World Cup final in 1991, added: "They've got to be able to do that week in, week out. A major plus is a great strength-in-depth in the squad, which probably no other northern hemisphere side has."
England, the 2003 champions, play Australia, Wales, Fiji and Uruguay in Pool A at the World Cup, starting on 18 September, with the top two going through to the quarter-finals.
Former Ireland and Lions skipper Brian O'Driscoll thinks fly-half George Ford, 22, will be vital to England's World Cup hopes.
"George is going to be England's World Cup 10 barring any injuries," O'Driscoll told the BBC.
"He brings a great variety. The one question mark is maybe his kicking under pressure - he missed a couple against Ireland.
"The rest of his game is fantastic and he will be world class if he can get his kicking game up to 80% plus."
O'Driscoll is also optimistic about the chances of Ireland, who suffered their only Six Nations loss to Wales.
"If we had won the Grand Slam there would have been an insane amount of pressure," he said. "It gives us an opportunity to slip in a fraction under the radar."