Williams himself has been on the receiving end of defeat to Italy and is under no illusions as to the challenge they will face against Nick Mallet's team, especially if they dictate the way the game is played.
"It's a back line determined to go out and play some rugby against a very strong Italian side," said Williams.
"Italy is a very proud nation and I think the supporters certainly get behind the players - it's quite an intimidating place to go, not Rome itself but Stadio Flaminio.
"What Italy tend to do, especially at home, is stop teams from playing. The game gets scrappy and gets a little bit more physical up front.
"I've lost out there in Italy, and there's no shame in that because they are a very good side.
"Italy always gets teams into playing a game that suits them - I think we saw that against Ireland when they didn't really let Ireland play any rugby whatsoever and that's what we've got to come away from on Saturday."