Manager Torey Lovullo said what's perceived to be a minor health issue will bench his ace for the opener.
Lovullo, speaking before Monday's spring training game against the Chicago White Sox, said the tightness Greinke experienced in his groin in his latest start last Wednesday led to him being ruled out for what is usually his opening-day role. Greinke left that game after one inning.
If there had been no health issue, Lovullo said, Greinke would be on the mound for Arizona on opening day for the third straight season.
"Every staff has a No. 1 and he fit the bill perfectly," the manager said. "He won 17 games last year. He was our staff ace."
Lovullo said he's not ready to name who will take Greinke's place in the March 29 opener at home against Colorado, although Robbie Ray would seem to be the logical alternative.
Ray had a breakout season a year ago, going 15-5 with a 2.89 ERA and making the NL All-Star team. The 26-year-old left-hander was third in the National League in strikeouts with 218 in 162 innings pitched.
The Diamondbacks don't believe Greinke's issue is serious. The right-hander said he felt good after a bullpen session Sunday and he is scheduled to start Wednesday against San Francisco. That would put Greinke in line for another start next Monday night in an exhibition game at Chase Field against Cleveland, then perhaps make his first regular-season appearance in the series finale against the Rockies on March 31.
"There's a lot of teams that go into spring and there are kind of question marks on the fourth or fifth guy, on who's it going to be," reliever Archie Bradley said. "To return five guys that all threw the ball really well last year is a big upside when you start the season."
Lovullo said the Diamondbacks are still figuring out the order they will pitch in.
Arizona opens with three games at home against Colorado, has an off day and then hosts the Los Angeles Dodgers for three.
"There's a strategy," Lovullo said. "We don't just look at opening day. We look at opening day and then beyond, so probably five or six days beyond that day. And we want to make sure that we hit things just right to get it to the point where we have good matchups all the way through."
Godley might be the sleeper among the returnees, although he had a rough outing Sunday, allowing four runs on three hits with two walks and seven strikeouts in 4 2/3 innings in a 6-3 loss to Cincinnati. Godley eventually moved into the No. 5 starter role last season following the injury to Shelby Miller. He started 25 games, going 8-9 with a 3.39 ERA. Walker was 9-9 with a 3.49 ERA and Corbin 14-13 with a 4.03 ERA.
One question mark, though, is the organizational depth at starting pitching beyond the first five.
"I keep hearing that pop up all the time," Lovullo said. "But look at it this way. Last year we had six starters (including Bradley). Archie falls into a tremendous role for us that helps us do the special things we did last year. Zack Godley steps up from player development. He's really kind of an unknown and turns out to be one of our staff savers."
Lovullo said the Diamondbacks "like a lot of names" of potential starters but the situation isn't as simple as it was a year ago.
"We had six really good starters (including Bradley)," he said, "but we feel like six through nine (this year) are going to be able to step into this environment and help us out in a special way."
Bradley, moved to the bullpen a year ago to become one of the game's best setup men, is a leading candidate to take over as closer. He said there is always going be a need for other starters beyond the opening five during the long season.
"Guys are going to go down," Bradley said. "You're just going to have guys step up. Whether it's kids from Triple-A, whether it's trades, that's what the good teams do."
Lovullo said he wants to name a closer this week, before the team moves to Chase Field for a pair of exhibition games against Cleveland next Monday and Tuesday.