PHOENIX -- There is a decision looming for the Arizona Diamondbacks. With left-hander Jordan Montgomery, who was signed as a free agent just before Opening Day, likely less than a week away from joining the rotation, one of the current occupants will lose his job.

That means every outing for Ryne Nelson and Tommy Henry is big, because one of them is expected to give way to Montgomery.

That was the backdrop as Nelson took the mound against the Cardinals on Saturday night, and manager Torey Lovullo said before the game he wanted to see how the right-hander would do at blocking out the “noise” and dealing with the pressure.

The answer? Just fine, thank you very much.

Nelson kept the Cardinals in check through six-plus innings as the D-backs evened the three-game series with a 4-2 win at Chase Field.

“Ryne Nelson went out there and executed a really good game plan,” D-backs manager Torey Lovullo said. “He pitched into the seventh inning. It couldn’t have been any better. He wiggled out of some jams, just really kept pressing the zone with his fastball, and working off that, he had a nice cutter. For me, he was in total command all game long.”

Montgomery had what was presumed to be his final Minor League tuneup start Saturday night for Triple-A Reno, so this could have been Nelson’s final opportunity to make his case to stay in the rotation.

If it was, his closing argument was a good one.

“I feel like command was really good today with pretty much everything I threw,” Nelson said. “I think I limited sliders and curveballs but everything else felt really good. I think the cutter was working really well and played off the fastball, so I think it was good execution today and good defense behind me, and I think it went pretty well.”

Nelson’s best work came in the sixth when St. Louis’ first two hitters reached base. He got Nolan Arenado to ground into a fielder’s choice, and after a flyout and intentional walk to load the bases, Nelson struck out Jordan Walker to end the threat.

As he walked off the mound, Nelson let out a yell of exhilaration. It was a rare show of emotion from the usually stoic pitcher, but it was well earned.

“I definitely appreciated Torey letting me get out of that,” Nelson said. “And second, third, no outs and you end up giving up zero, I think anybody would let out a little celebratory scream.”

It wasn’t just that Nelson got out of that inning that showed his growth, but the way he went about it.

“Typically, in the past, I would just try to throw heaters by them and get mad and stuff like that,” Nelson said. “But today, it's just like, deep breath and try and execute.”

The competition between Nelson and Henry is nothing new. Heading into Spring Training, before the injury to lefty Eduardo Rodriguez and the signing of Montgomery, the two good friends were competing for the No. 5 spot in the rotation.

Because Rodriguez got injured and Montgomery needed some Minor League starts after missing Spring Training, the two are once again in a competition.

“We do have a very tough decision,” Lovullo said. “And as I outlined a little bit in pregame, I want everybody to block out that black noise and just go compete. Zip up the bubble and just go out there and let it eat. You’ve got to block out a lot in this game and Nelly did a great job of that.”

Nelson has had plenty of practice at that.

“It's kind of similar to the way it is in spring the past few years,” he said. “Just focus on myself and try to go out there and compete as best as I can. Try to get better every day.”