Showalter was deciding between Gonzalez and Bud Norris, who has been available to pitch in relief.
Gonzalez performed some fielding drills this afternoon with head athletic trainer Richie Bancells and didn't experience any discomfort related to the groin strain that forced him out of Sunday's game in Toronto.
"It feels pretty good. I don't feel any pain, so I'm just ready to go whenever they tell me," Gonzalez said before receiving confirmation that he was starting Saturday.
"I'm excited. I want to be on the mound anytime I can to help out the team. That's what we're here for.
"Buck told me earlier, 'Hey, if you feel anything, just let us know. We don't want to push it and get it worse.' Good thing there's a lot of guys out there and a lot of pitchers. We're not worried about that."
Gonzalez has a career 2.54 ERA on five days rest.