The Hawks waited until seeing Carroll test his sprained left knee before finalizing their starting lineup less than 30 minutes before the game.
Carroll participated in a shootaround that was closed to media earlier Friday. He then took shots and drove to the basket on the team's practice court about an hour before the game. He showed enough mobility and quickness to convince coaches and the training staff he could play.
Before that warmup session, the Hawks had listed Carroll and Kent Bazemore together in the small forward spot as the team waited to declare a starter.
Carroll was injured on a drive to the basket in Cleveland's Game 1 victory. He looked seriously injured, unable to put weight on the leg, when helped off the court.
An MRI showed no structural damage. Carroll was diagnosed with a sprain and bone bruise.
Carroll's knee appeared to buckle as he was driving to the basket with about 5 minutes left in the Game 1 loss to the Cavaliers on Wednesday night. Carroll couldn't put pressure on the leg as he was helped off the floor.
The fear was Carroll had suffered a significant injury that could end his postseason.
The loss of Carroll could have been devastating to the Hawks' hopes of beating LeBron James and the Cavaliers.
At 6-foot-7, Carroll provides the size needed for the difficult matchup against James, who led the Cavaliers with 31 points in Wednesday night's game.