Now Pembroke-born Thomas is looking forward to taking his RBS 6 Nations bow against Scotland on February 14.
Skipper of the Ospreys this season following Scott Gibbs' retirement, Thomas has a modest take on his international development since he made his debut on Wales' short summer tour of Australia and New Zealand in 2003.
"It was great playing in the World Cup, but I would just love to figure in the Six Nations," said Thomas.
"I suppose it's strange to play in a World Cup before taking part in the championship.
"But in some ways, playing in the Six Nations would mean more because it's the tournament I grew up dreaming of playing in. It's got such history.
"I have real memories of Wales beating England in 1993 at the Arms Park when I was 10, and of course, the Wales-England match in 1999 at Wembley.
"But although I'd love to play this year, it's going to be very difficult to break into the Wales side.
"The back-row is a competitive area, what with Dafydd Jones, Colin Charvis, Martyn Williams and Alix Popham all playing well."