And lightning wing Williams expects the Red Roses' newly-sharpened threat out wide to give the visitors a rough ride at HQ.
Williams, 32, said: "England have selected a lot of quick players in the backline. In fact, they have some of the quickest in world rugby.
"I'm sure they will be intent on running with the ball and scoring tries. We're expecting a really tough battle. But a lot will depend how the forwards play.
"England have a strong and physical pack and will aim to earn the right to get the ball wide and put the speed merchants in behind.
"You can't be one-dimensional and I'm sure they will try to use all their traits and weapons to break us down. But we'll be ready."
Ospreys ace Williams notched up a pre-Twickenham mental edge with victory over Leicester Tigers in the Heineken Cup almost two weeks ago.
But the former IRB Player of the Year has warned his team-mates of avoiding complacency ahead of the trip to London.
Williams added: "There is a slight psychological advantage having beaten a very good English team from the Guinness Premiership.
"We'll be confident going to Twickenham but we won't get carried away.
"Just because we beat Leicester does not mean we'll beat England. It will be a different story and a different animal.
"The England squad is strong on paper and I'm sure Martin Johnson and his men will feel like they have a point to prove. What better way for them to do that than beat Wales at home."
While Wales' record try-scorer lines up in his familiar position for his 69th cap, regional colleague James Hook starts for the first time alongside Lions star Jamie Roberts at outside centre.
But Williams has backed creative star Hook to make a real impact by testing England's defence to the limit.
Williams said: "You can put James anywhere on the field. He was almost thrown onto the field at 15 during the autumn and was probably our best player of the series.
"He's a tremendous player and one of the most naturally gifted players I've ever played alongside. He can create something out of nothing.
"I'm looking forward to playing outside him on the wing. He's never let the side down before and I know he will do a job for us."