Hamilton took the field before Wednesday's game and participated in batting practice.
"I don't know the test results yet, but I do know he feels great," Price said. "And today … he'll be able to do some outdoor baseball activity -- catch some fly balls, throw, hit live on the field. And that will definitely be kind of the final checklist. If he passes the test, before he's able to go back and start playing again, potentially as early as tomorrow."
Hamilton suffered the concussion when he was hit in the head sliding into third base on June 8 against the Cardinals. He was batting .417 (10-for-24) in June before the injury.
• Price said he's waiting until after Thursday's game to announce who will start Saturday against the Astros. The spot in the rotation previously belonged to right-hander Daniel Wright, who allowed five runs (three earned) across three innings against the Braves on Monday, before he was sent down to Triple-A Louisville on Tuesday.
Pat James is a reporter for MLB.com based in Atlanta. This story was not subject to the approval of Major League Baseball or its clubs.