"Coming off was just precautionary and it's responding well to treatment," said Rhys.
Williams made his Test debut against Ireland in 2000, which was the last time that Wales managed to beat their Celtic rivals.
That victory came away at Lansdowne Road, as Wales hung on to win a tight match by 23 points to 19.
"I've got great memories of that day for my first cap and obviously winning the game, so it would be nice to relive some of those memories this Saturday," Williams said.
"But the Irish side has come of age over the past few years, always being in contention, knocking off the big guns, and shows how difficult a task it will be to beat them."
You can see the Wales team first at Cardiffblues.com courtesy of the BBC news feed on the home page of the site.