SCOTTSDALE, Ariz. -- Manager Torey Lovullo won't say it yet, but he has laid out the pieces of an equation that add up to Zack Greinke missing his projected Opening Day start.
Greinke is recovering from tightness in his right groin that took him out of last Wednesday's game, but at this point, the injury is minor compared to the setback of only throwing one inning and 19 pitches, as he was building arm strength for Opening Day.
Greinke's next start would have been Monday against the Angels, followed by a Saturday split-squad start against the Royals, setting him up for the Opening Day bid against the Rockies on March 29. He will throw a bullpen session Sunday -- at least a day behind his normal schedule -- and the rotation questions should clear up based on the outcome of Sunday's session.
"He will 100 percent not start on the 19th," Lovullo said of Monday's scratch. "I guarantee that."
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Lovullo also said that he wants Greinke to throw at least 65-70 pitches before he starts a regular-season game, and having only thrown 19 pitches on Wednesday means he probably won't be targeted in that range in his next start. He'll need two starts to get into the range Lovullo wants him, and that will mean missing Opening Day, but likely being ready for the third game of the season.
"To go from 19 pitches back up to 60 or 70 is probably not feasible," Lovullo said. "If we get through the bullpen, we'll pick a good number that's comfortable for him. Step one is to get him through tomorrow and see how he feels."
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Big action on the back field
With the division rival Padres playing in the stadium, Lovullo sent three pitchers to the back fields to pitch against a team of Angels Minor Leaguers. No. 4 starter Patrick Corbin threw 78 pitches over five innings, allowing one run on four hits and a walk, while striking out five.
"It was good to keep building up," Corbin said. "That's really all it's about right now. I feel like the ball's coming out pretty good. Slider felt really good. I had a lot of lefties today, so [the slider] was something we worked on a little bit more."

Left-hander Jorge De La Rosa threw two innings of scoreless ball, allowing a hit and a walk and striking out one. Closer candidate Yoshihisa Hirano threw one inning, allowing one walk and no hits, with one strikeout.
Little things on the big field
The D-backs played to a 3-3 tie with the Padres, paced by a strong start from Ryan Atkinson, who threw three no-hit innings, allowing three walks and striking out four.
Chris Owings was 3-for-3, igniting the offense with a leadoff single and a stolen base in the second. He advanced to third on a grounder from Daniel Descalso and scored on Nick Ahmed's sacrifice fly.
"We were able to do a lot of little things right," Lovullo said. "[Paul Goldschmidt] with the big [two-run] home run [in the fifth]. When your main guys are starting to click and put things together, it means the spring is closing and the start of the season is nearing. It's good to see."
Christian Walker made a standout play at first base in the eighth, running into foul territory in right to catch a ball, then whirling to throw out the runner at home for an inning-ending double play.
Medical tent
Jeff Mathis hasn't played in a Cactus League game since Wednesday due to lower back tightness.
"Jeff is doing just fine," Lovullo said. "At this point in the year, getting close to the start of the season, we decided to just hold back and rest him a little. Nothing that's going to require, hopefully, an extended shutdown period or an MRI. We wanted to pull back and just use a little extra caution. You might not see him for the next couple days, but he's eager to get back in there."
Randall Delgado began a throwing program on Saturday, a good sign that he's on the road to being ready for game action, though it will be a challenge for him to be ready by Opening Day.
Up next
The D-backs head to Goodyear for a 1:10 p.m. MST game with the Reds on Sunday. Fifth starter Zack Godley gets the ball, with notable relief work scheduled from closer candidate Archie Bradley, along with Jimmie Sherfy, who will be making his first Cactus League appearance as he competes for a spot in the bullpen.