Arizona Diamondbacks right-hander Merrill Kelly will be sidelined for "a month" or more with a shoulder injury, manager Torey Lovullo confirmed.

Kelly was scratched from his start on Sunday with a teres major strain in his right shoulder and was placed on the 15-day injured list on Tuesday.

Lovullo said two MRI exams confirmed that Kelly will not need surgery, but the team is still gathering more medical opinions to determine a timetable.

"We're not looking in terms of weeks as what we had hoped for," Lovullo said, per the Arizona Republic. "So I think the next step up is a month, more than that."

Asked if Kelly would be back before the mid-July All-Star break, Lovullo answered, "I don't know. Hard to say."

Kelly, 35, is 2-0 with a 2.19 ERA through four starts this season. He is 50-43 with a 3.75 ERA in 131 starts since making his debut with the Diamondbacks in 2019.