CLEVELAND -- Travis Hafner's surgically repaired right shoulder has responded well enough to rest that he's ready to go out on a rehab assignment.

Pronk, who was placed on the 15-day disabled list April 29 with shoulder soreness, will report to Triple-A Columbus on Friday to begin an assignment that can last up to 20 days.

"The [expected] length has yet to be determined," head athletic trainer Lonnie Soloff said.

Hafner has been taking batting practice at Progressive Field this week, with positive results. His shoulder condition will continue to have to be monitored all season, as he is seven months removed from arthroscopic surgery.

In 17 games this season, Pronk batted .270 with four homers, five doubles and eight RBIs. The Indians were encouraged with the strides he had made in terms of bat speed and pitch selection after missing half of last season with shoulder weakness.