Williams will not be allowed use of a catapult to floor his opposite number - but the diminutive speedster is determined to strike a blow for the smaller man in any way he can.
"It's David versus Goliath," he said.
"I don't think he's going to bother trying to run around me but I've played against the big wingers all my life.
"With my physique, that's going to happen anyway. They are all pretty much monsters for me.
"I've played against some big lads, the likes of Aurelien Rougerie and Alesana Tuilagi. That's my job and that's what I've got to put up with.
"I tend to find it easier playing against the bigger man, to be honest.
"I've just got to find methods to deal with the bigger lads. I'll have to go low or he could be chucking me into the stands I imagine.
"It's a case of any means possible within the law I suppose. You've got to deal with it, you've no other option."
Williams, one of a record 13 Ospreys in the Wales starting line-up for Saturday's opening RBS 6 Nations clash, did not face Gloucester giant Vainikolo in the Heineken Cup - and took some ribbing for it.
He said: "When we played Gloucester away in the Heineken Cup, I missed the game through injury. The lads seemed to think I pulled out of that one, but, believe me, that wasn't the case!"
The headlines this week have been stolen by Wales head coach Warren Gatland's decision to base his selection almost exclusively on the Ospreys.
Gatland was hugely impressed by their powerful performance in beating Gloucester 32-15 to reach the Heineken Cup quarter-finals - and wants to infuse the national set-up with the same confidence as Wales look for a first win at Twickenham in 20 years.
Gatland has already spent time coaching the Ospreys this season, working in particular on their scrum and driving maul, and their blitz defence is the same system championed by Shaun Edwards.
But Williams insists it will be Wales and not "Ospreylia" who will run out at Twickenham this weekend.
"I hope there are going to be a few surprises. We are being coached by a different coaching staff and we are going to play the Welsh way rather than the Osprey way," said Williams.
"I don't think we can afford to mirror what the Ospreys do because a lot of those England lads have played against us.
"Even though there are a lot of Ospreys boys involved, it's still Wales and we need to play the way that we feel is going to beat England."