The two young left-handers will square off at Coors Field on Friday night, when the D-backs and Rockies open a four-game series.
The D-backs' slim playoff hopes took a major hit on Thursday, when a ninth-inning rally came up short in a 6-5 loss to the Padres. Coupled with the Cardinals' win against the Astros, Arizona is now 5 1/2 games out of the second NL Wild Card spot with 13 games to play.
Arizona will turn to Miley as it begins its final road trip of the season, to Colorado and San Francisco. The 25-year-old is 15-10 with a 3.10 ERA, putting him in competition with Cincinnati's Todd Frazier and Washington's Bryce Harper, among others, for rookie honors.
Miley has struggled as of late, with a 4.85 ERA in his last four starts. He took a loss against the Giants last Saturday, giving up three runs on eight hits in seven innings.
"Just was struggling with location early in the game," Miley said afterward. "Kind of battled through that and made some better pitches later on."
Miley will face a Rockies club that just suffered a four-game sweep against San Francisco. Colorado has lost six straight and 13 of 15 as it opens its final homestand of 2012.
Pomeranz (1-9, 5.06) has lasted four innings or fewer in eight of his last nine starts, thanks in part to the Rockies' strict pitch counts. The 23-year-old made it through three frames on Saturday at San Diego, giving up four runs on four hits.
D-backs: No rest for Montero
Catcher Miguel Montero started his 18th consecutive game behind the plate on Thursday, when Arizona played a day game after a night game. The streak sets a franchise record, obliterating the previous mark by seven games.
The 29-year-old went 1-for-4 and has hit safely in all but two contests during this stretch, posting a .373 average overall.
"There's no time to be tired or fatigued, it's time to push it," Montero said before Thursday's game. "We're in our last lap right now, we only have  games left, just have to leave it all out there."
Rockies: Hamstring issues flare up for CarGo
Left fielder Carlos Gonzalez didn't start the first two games of his team's series against the Giants because of a hamstring injury. He went 0-for-4 on Wednesday, then 0-for-1 on Thursday afternoon before leaving with tightness in the left hamstring.
Catcher Wilin Rosario made his first career start at first base on Thursday and went 3-for-4, with Jordan Pacheco moving behind the plate. The Rockies want to keep Rosario's bat in the lineup, but he has struggled defensively at catcher, and a brief trial at third base didn't pan out.
"The guy [Rosario] has 25 home runs," manager Jim Tracy said. "If you have the opportunity to place 25 home runs in the lineup, you want to do so, instead of leaving him off to the side and waiting for one at-bat."
The D-backs lead the season series 6-5, with seven contests remaining.
Miley has a 1.88 ERA in 24 career innings against the Rockies. His only start at Coors Field came last Sept. 5, when he held the Rockies to two runs over seven innings.
The D-backs reached Pomeranz for five runs in 4 1/3 innings on April 15.