Wales head for a two-Test series this summer and Roberts will face a South African centre pairing robbed of both skipper Jean de Villiers and the experienced Jaque Fourie through injury.
But Roberts insists there is no way a Wales team, that will be without fellow Lions Leigh Halfpenny, Sam Warburton, Richard Hibbard and Justin Tipuric can be afford to be anything below their best.
"They are going to have to come up with a new centre partnership and we have to try and take advantage of that," said Roberts, who scored a try during the decisive third Test win for the Lions against Australia last summer.
"We will try and see it as a weakness but they have strength in depth as a country.
"They can replace like for like and not lose much.
"De Villiers is a big loss for them but they have guys like Jan Serfontein and JJ Engelbrecht who are top-notch player
"They are a huge, proud rugby nation and I have been there with the Lions, Wales, the Sevens, my school team. I have been there with almost every team I have played for and it never disappoints.
"The culture and honesty of the people makes it an incredible place."