Harris will serve as a bulk reliever behind opening pitcher Shintaro Fujinami in Tuesday's game versus the Rays, Martin Gallegos of MLB.com reports.
Harris will follow Fujinami for the second time this month after he allowed two runs on five hits while striking out five batters over five innings June 2 in Miami. The 26-year-old owns a 3.00 ERA and 0.93 WHIP with a 7.2 K/9 over 15 innings in his last three outings, and he'll look to continue his productive run as the Athletics attempt to extend their six-game win streak Tuesday.