Oller was called up from Triple-A Las Vegas and will start Sunday's contest against the Astros, Matt Kawahara of the San Francisco Chronicle reports.

EDGE Analysis

Oller will return to the big leagues after being optioned to Las Vegas on June 30, returning to start the Athletics' final game before the All-Star break. The 27-year-old owns a 9.00 ERA and 2.04 WHIP over 23 innings this season, but in the month of June he was able to compile a 3.24 ERA and 1.80 WHIP over 8.1 frames in five appearances. Jared Koenig was optioned to Triple-A on Sunday to open a roster spot for Oller.