Carter probably out for Sunday.

Byline: Dennis Georgatos

Rookie defensive end Andre Carter will keep a protective boot on his sprained left ankle until at least Friday, and chances are he'll miss the 49ers' game at Indianapolis on Sunday.

Carter, who has started in all nine games, has two sacks to tie for the team lead with three others. Though he's officially listed as questionable, Carter said the risk of aggravating the injury made it unlikely he would be available. He suffered the ankle sprain Sunday during the second quarter of a 25-22 overtime win at Carolina.

"I don't want to put myself or the defense in a position where if I played this next week, and I'm not quite ready, I …