Mayo (back) is serving as the Orioles' designated hitter and batting fifth against the Rays on Wednesday, Jacob Calvin Meyer of The Baltimore Sun reports.
Mayo was out of the Orioles' lineup in each of the team's last four games due to back soreness. He'll be eased back into action as the DH in Wednesday's game, but he could return to fielding duties for Baltimore's series opener against Toronto on Thursday. Mayo has gone 11-for-52 (.212) with two home runs, six RBI and a 4:19 BB:K since May 1.