Arizona Diamondbacks right-hander Zack Greinke's next bullpen session has been pushed back, putting his availability for Opening Day in jeopardy.

He left Wednesday's spring training game against the Cincinnati Reds with right groin tightness.

"Obviously when you're talking about potentially pushing him back and not having him ready for Opening Day, my concern level goes up," Arizona manager Torey Lovullo said. "But I know it's a situation that's going to be a very positive outcome. ... I feel very strongly that he'll be in there as quickly as he possibly can."

Greinke allowed one hit and zero runs, striking out two, in one inning before departing Wednesday.

"It seems pretty small at the moment," Greinke said of the injury after the game. "Hopefully not a long-term thing."

The 34-year-old had acknowledged earlier in camp that his velocity has been down. He had two more scheduled starts before Opening Day.

Last season, Greinke went 17-7 with a 3.20 ERA, finishing fourth in National League Cy Young voting.