Roberts returned to the Blues setup two months later and played in the 14-man Blues victory away to Gloucester which saw the Blues become the fifth team to win all their games in the Heineken Cup group stage. Roberts was then selected in the Welsh squad for the 2009 Six Nations Tournament. For the opening match against The Scots, Roberts was once again selected to play outside centre for the first time with Gavin Henson inside him, but Henson pulled out with another injury. Roberts played an instrumental game, winning a man of the match award in the 26–13 win. He was again selected for the match against England. This time he was better marshalled with England flanker Joe Worsley man marking him for the entire game as Wales won 23–15. Roberts played again at 12 for the game against France. This time he was kept quiet and was replaced midway through the second half by Gavin Henson. Wales lost 21–15. For the third time, Roberts was selected at outside centre with Gavin Henson, and he finally played with him. But the combination didn't go as well as it was tipped to be with Roberts barely touching the ball the whole match. Wales won 20–15 but not by the amount they were hoping for, as they were looking to increase their points difference for the final round. Roberts was put on the bench for the tournament decider against Ireland. He came on just before halftime as Lee Byrne was injured. Roberts failed to match Brian O'Driscoll, who scored a try, as Ireland claimed victory 17–15 to win the Grand Slam for the first time in 61 years.