Upton hurt his left hamstring while running the bases Tuesday and was forced to leave the game after the first inning with tightness.
"We're going to give him another day," manager Kirk Gibson said. "I knew what he did, I saw it happen, I think there needs to be more comfort."
Upton went through conditioning drills early Friday afternoon and reported afterward that he felt fine. The outfielder even tried to convince his manager to play him, but the effort was fruitless.
"It didn't go well, they had already made their mind up," Upton said. "It's just gotten better day by day. It was just tightness, that's the word everybody likes to use. It's good to go now."
As for him getting claimed off waivers, Upton brushed off the report with little concern past the initial shock value.
"It surprised me a little bit, but it's nothing," Upton said. "If it's important, somebody will tell me. But it's nothing."