Rea, who is competing for one of the club's two rotation vacancies, struggled early and lasted only three innings (a step backward after his five-frame start on Saturday). The 25-year-old right-hander allowed five earned runs on six hits and a pair of walks, while striking out three.
For the D-backs, left-hander Anthony Banda got the start, with Zack Greinke throwing on a practice diamond at the club's Salt River Fields complex. Banda, the No. 16 prospect in the organization, went three innings and allowed four runs (three earned) on four hits.
Wil Myers opened the scoring for the Padres against Banda with a solo home run to the opposite field in the bottom of the second. The Padres plated three more runs in the inning, as Melvin Upton laced a two- run double and came around to score later in the frame on a balk.
Leonel Campos, Luis Perdomo and Carlos Villanueva all pitched scoreless frames in relief for the Padres. But veteran left-hander Matt Thornton, who hadn't allowed a run all spring entering Thursday, was touched up for four runs in the seventh.
"Everybody has those kinds of days," Padres manager Andy Green said of Thornton, who is fighting for a bullpen spot. "He has had them few and far between over the history of his career, so it was just one of those days for him."
Up next for D-backs: The D-backs play host to the Indians on Friday at 1:10 p.m. MT at Salt River Fields, with Shelby Miller getting the start. Evan Marshall, who is competing for the final open spot in the bullpen, is also slated to pitch. The game is on MLB.TV.
Up next for Padres: With manager Andy Green (and half the club) on its way to Mexico City for games over the weekend, bench coach Mark McGwire will be given managerial duties on Friday as the Padres face the Rangers at 6:05 p.m. PT in Surprise, Ariz. Opening Day starter Tyson Ross, who has struggled a bit this spring, will make his penultimate Cactus League appearance. The game can be heard on Gameday Audio.
AJ Cassavell is a reporter for MLB.com. Follow him on Twitter @ajcassavell. This story was not subject to the approval of Major League Baseball or its clubs.