O'Neill (back) will begin a rehab assignment with Triple-A Memphis on Tuesday, John Denton of MLB.com reports.

EDGE Analysis

O'Neill will serve as Memphis' designated hitter Tuesday before eventually playing the outfield, provided he passes a variety of stress tests. The outfielder has been on the shelf since early May with a lingering back injury but finally began experiencing improvement following a pair of injections last month. O'Neill could return shortly after the All-Star break if all goes well.