Evan Gattis (back) will begin a rehab assignment with Triple-A Gwinnett on Thursday. The date had been up in the air, but now it's set. Gattis took batting practice with the Braves' Low-A Rome club for a few days before being cleared for game action. He'll be Gwinnett's designated hitter Thursday and is slated to play 3-4 games there, putting him on pace to be activated Monday at the earliest. Gattis has been out since late June with a bulging disc in his upper back.