Cashner, after allowing a run in the first inning, retired 11 consecutive hitters before he issued a walk to Alfredo Marte to start the inning. Cliff Pennington struck out before a Didi Gregorius double to right put runners on second and third base with one out.
That's when things got interesting.
With the infield in, Collmenter dribbled a ball to rookie second baseman Cory Spangenberg, who threw home to Rene Rivera, who attempted a sweep tag of Marte, who was called safe as the D-backs took a 2-1 lead.
San Diego's Bud Black used his manager's challenge but the call stood after a review. The D-backs added a second run in the inning when Gregorius scored on a botched rundown as a throw from Rivera glanced off the glove of third baseman Yangervis Solarte. Finally, David Peralta had an RBI single.
Rivera wasn't happy at all with the call.
"The first thing the ump [Cory Blaser] told me was his right foot touched the plate," Rivera said. "I told him, 'No, it didn't.' He was out. It's clear."
The way this season has gone, Arizona manager Kirk Gibson wasn't about to complain about anything that resembled an offensive outburst, even if they were mostly ground balls.
"We needed some breaks, so it's about time," Gibson said. "We've been struggling to score some runs."
Just when it appeared Cashner (2-7) was starting to cruise, he was tagged with three runs in the inning.
"I thought the fifth inning was tough and could have gone either way," Cashner said. "If Collmenter hits that a little harder, it's not close at home. The whole inning was really weird. It was one of the more challenging things I've had."
All told, Cashner allowed four runs (two earned) on five hits over seven innings with one walk and five strikeouts in his third start since returning from the disabled list.
"He threw the ball fine," Black said. "He was the victim of circumstance. That inning got away from us."
It might not have mattered with the way Collmenter was pitching.
Collmenter (10-7) allowed five hits with two walks and three strikeouts. He's 3-0 against the Padres this season with two earned runs allowed in 20 2/3 innings.
"It's a weird delivery. He's right on top and his fastball is anywhere from 85 to 88 [mph] and his changeup is good," Rivera said.
The D-backs (58-81) gave him a 1-0 lead in the first inning on an RBI triple by Peralta. Miguel Montero added an RBI single in the eighth inning to make it 5-1.
Trailing 1-0, the Padres (66-72) tied the game in the third inning when Alexi Amarista singled and then scored when Seth Smith doubled into the right-field corner.
Two Padres pitchers made their Major League debuts in relief -- 27-year-old right-hander Leonel Campos and 23-year-old righty R.J. Alvarez.
Campos got the final two outs of the eighth inning on a double play without allowing a run. Alvarez wasn't as fortunate, as he allowed one run on one hit with two walks while retiring two batters in the ninth.
"These guys have big arms," Black said. "It's good to get these guys acclimated."