The Richmond full forward looms as a pivotal figure in the season opener, but the Blues' coach is without regular full-back Michael Jamison through suspension and doubt remains over the fitness of fellow key defender Paul Bower, who rolled an ankle in a practice match last week.
Bower took part in Carlton's final training session on Wednesday, as did Simon White, Bret Thornton and Matthew Watson, with any one of those three in line to get the tough job on Riewoldt if Bower's ankle doesn't respond well to the 30-minute hitout at Visy Park.
"With Jamo out, I think it's opened up the possibilities for a few guys," Ratten said.
"The person who gets that role will have a great opportunity to really project their career and maybe make a name for themselves.
"Jack's a great player, he's a Coleman Medallist, and his impact on the game will be critical to us. If we can limit that then we'll go a long toward winning the game."
Luckless onballer Brock McLean did not take part in the session due to an ongoing ankle issue and will play in the VFL at the weekend.
More to come.
Paul Bower is a 261,200 defender in the Toyota AFL Dream Team competition.
