Tareta-Junior Siakisini wants payback on Roberts for his role in helping Wales beat Samoa in the 2011 World Cup and he aims to take his one shot at revenge, even if he knows he faces a mighty task to do so.
"My heritage is Samoan, and everyone knows about Wales being in the same pool as Samoa at the last World Cup," Siakisini told Australia's Telegraph newspaper.
"There is nothing you can dislike about the guy. He is a hard player who gives it his all, a giant who can run fast.
"It's unbelievable that I'm going to get the chance, every centre in the world knows that's going to be a hard job.
"I'm just going to do my best and try to stop him, but he's a world-class player so who knows what will happen?"
Siakisini freely admits that stopping Roberts in his tracks is unlikely to be easy and that attitude is echoed by the Combined Country head coach, Cameron Blades.
The former Glasgow prop, who played against The Lions twice in 2001 with Australia A and the Waratahs, knows his men will be up against it given the amount of talent on show for the tourists' today.
But, while he makes no attempt to disguise the fact that there is a gulf in experience between some of his players and those in Warren Gatland's squad, Blades knows his men won't lack for guts, integrity, pride or workrate as they face what he describes as a 'massive challenge' head on.
"A lot of the guys are from remote regional areas. We know those folk come with a real work ethic and a never-say-die-attitude and that is a great thing," said Blades.
"If every coach went into a camp knowing those things were already ingrained in their players, three quarters of the job is done.
"All I've said to the boys is that we've got nothing to lose and they've got everything to lose.
"They have two arms and two legs just like us. Once you get over the fact that they're all international players, you can just play.
"Obviously, a few of the younger guys will get butterflies, but you generally find that once the game is a minute or two old it is just another game and their instincts kick in."