"It's an ankle issue, something he just kind of tweaked," manager Brad Mills said. "Last night he warmed up, but couldn't get it loose." Mills said the ankle wasn't sprained.
Cruz, who is 1-0 with a 2.08 ERA in seven appearances, has had three appearances lasting more than an inning. He hasn't appeared in a game since Monday, when he tossed 1 2/3 scoreless innings in Milwaukee.
Cruz was expected to throw prior to Saturday's game to test the ankle, which Mills said he initially injured during pregame warmups last week.