Shane Williams has warned Wales that they will come up against an England team with a strength in depth matched only by the All Blacks when they head to Twickenham on Saturday.
Warren Gatland's men are on a high following their stunning 34-7 victory over Scotland in Cardiff last weekend, raising hopes that they could cause an upset against the defending champions.
Williams insists Wales are more than capable of victory over Eddie Jones' side but believes the strength of England's bench, which boasts names such as Ben Te'o and Jack Nowell, could be decisive.
"I think Wales are good enough to win but I just think England's strength in depth is up there with the All Blacks," the legendary wing told Omnisport.
"They've got some world-class players now coming off the bench to strengthen that squad.
"I think it's a real tough ask for Wales. I do think they can win it, but I think England have got to be the firm favourites at Twickenham. It's not an easy place to go and play."
Wales - featuring 10 Scarlets players in the starting XV - ran in four tries in a thrillingly expansive display against Scotland, making light of injuries to a host of key players, including Sam Warburton, Taulupe Faletau, Liam Williams and Dan Biggar.
"I think they probably played better than a lot of us expected," said Williams, who won 87 caps for Wales. "I knew the team had the potential to do it and we've seen Scarlets do it week in, week out in the Pro14.
"A little bit surprised I suppose, but that's the style of rugby we've been wanting them to play for a long time and now Warren's brought it in and introduced it.
"They look very comfortable doing it. My concern is whether they can keep doing it.
"England is going to be a little bit different. I think defensively they're going to be far sharper and quicker to put Wales under pressure.
"But it's a step in the right direction and we beat a team that a lot of people were saying we were going to lose to."
Gatland has named an unchanged side for the trip to Twickenham, retaining his sizeable contingent of starting Scarlets.
"I think having a lot of those Scarlets players definitely helped the performance on the weekend," added Williams. "The familiarity of the players around them, they looked very comfortable.
"When [Aaron] Shingler was in the middle of the field or Rob Evans, they connected well with Rhys Patchell and the other boys and looked very dangerous.
"They're all singing off the same hymn sheet and that was a big part of it.
WALES | Unchanged starting XV for Saturday's #SixNations clash against England. 12 Scarlets in matchday 23! #inthepack-- Scarlets Rugby (@scarlets_rugby) February 6, 2018
CYMRU | Dim newid i'r tîm cyhwynol ar gyfer dydd Sadwrn, 12 Scarlet yn y garfan! #ynypac
Cymraeg https://t.co/n4FfodUBzd] pic.twitter.com/EAFXqUkzjG
"The magic now is to blend in players from other clubs, get them all playing the same style of rugby and it's great that they are playing the style that Scarlets are playing but obviously the national team should be stronger.
"But it's very positive and it was good to see the lads playing with a smile on their face."
With Rugby World Cup 2019 on the horizon, Shane tackles the best Japan has to offer in his new online series Shane Williams: Big In Japan https://www.facebook.com/shanebiginjapan
To discover the wonders of Japan for yourself: http://visitjapan2019.com/ #EndlessDiscovery