The veteran centre has been recalled to Argentina's starting line-up for the Millennium Stadium Test against Wales, having sat out the Pumas' Rugby Championship campaign.
It will be the Stade Francais back's 79th cap for his country, but his return will see him face the responsibility of coping with the abilities of Roberts, who is back in the Wales team having missed the tour of Australia after undergoing knee surgery.
Contepomi said: "It's a huge challenge. It's like climbing Mount Everest.Jamie is one of the best centres in Europe and one of, if not the best in the world.
"As a player you want to play against the best and I'm looking forward to having that challenge on Saturday. It's delightful to watch him play but it's not so good when he's in front of you as Jamie has that extra X-factor."