D-backs left-hander Madison Bumgarner, who is on the injured list with a mid-back strain, could be nearing a return following a simulated game on Sunday.

That’s a good thing, because the D-backs are going to need a starting pitcher after having to scratch Merrill Kelly just about an hour before his scheduled start against the Rockies on Monday night at Chase Field.

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Kelly was placed on the 10-day injured list with right shoulder nerve impingement and right-hander Riley Smith was called up from the team’s alternate training site. Taylor Clarke stepped in for Kelly in the series opener and allowed two runs (one earned) on four hits over four innings, striking out four in the D-backs' 3-2 loss.

The shoulder injury is something Kelly said that has been ailing him for about 10 days, but it got worse Monday.

Kelly said he believes the plan is that he will go to Dallas to be examined by Dr. Gregory Pearl of Texas Vascular Associates.

An MRI exam and ultrasound taken of the shoulder did not show any blockages or clots or interrupted blood flow, Kelly said.

“I don’t know,” Kelly said when asked whether he would be able to return this season. “Today was step one, just acknowledging the fact that I needed to deal with this and not try to press through it. But after today, I honestly haven’t dove into the schematics of what’s about to happen moving forward.”

D-backs manager Torey Lovullo said the team has not decided what to do about Kelly’s rotation spot, but the positive reports about Bumgarner’s 70-pitch simulated game Sunday would seem to vault him to the top of the list.

The scheduling would also work out nearly perfectly, with Bumgarner getting one extra day than usual before sliding into Kelly’s spot on Saturday against the Giants.

“I got word that he threw 70 pitches, felt good,” Lovullo said. “And actually, right before I came in here, we were trying to sit down and clearly get his input through the medical team and figure out what the next steps are moving forward. We’re developing some thoughts and a game plan as to what we’ll do, and we just know that he’s in a good spot and feeling very, very good.”

Bumgarner left his start Aug. 9 against the Padres after two innings due to the back issue, and he was placed on the injured list the next day.

Since then, he has thrown a couple of simulated games as well as bullpen sessions.

Diminished velocity had been an issue for Bumgarner in each of his four starts and Lovullo said he believes there was at least a slight uptick in it during the sim games, but he did not have the exact figures.

“I think the velo ticked up a little bit,” Lovullo said. “Secondary stuff, some said it was as good as they’ve seen it since the start of the season, and that’s the breaking ball and the cutter. So I think everything is coming together very, very well for him. It was very encouraging news when I heard that report today.”

If Bumgarner takes Kelly’s spot, that would allow Alex Young to remain in the rotation. Young has performed well filling in for Bumgarner.