DENVER -- The seventh inning was the key to the Arizona Diamondbacks' success Tuesday.

Arizona struck for four runs in the seventh during the nightcap of a doubleheader to beat the Colorado Rockies 5-3 and complete a sweep.

In the opener, the Diamondbacks scored three times in the seventh en route to a 6-4 win.

Pinch hitter Aaron Hill doubled home two runs in the second game, and center fielder A.J. Pollock hit a two-run homer as the Diamondbacks capitalized on spotty Colorado relief pitching to sweep their second doubleheader this season at Coors Field. The other was May 6.

The Diamondbacks grabbed a 1-0 lead in the first on first baseman Paul Goldschmidt's 27th homer, but they were limited to three hits and no runs through the next five innings before their game-winning rally.

"It was really good to have nothing going and all of a sudden find something late in the game like that," Pollock said.

In the afternoon game, second baseman Phil Gosselin, coming off an 0-for-4 performance in his Arizona debut Monday, hit a three-run homer and drove in four runs while going 2-for-3 with a double and two walks. Patrick Corbin got 11 outs on ground balls as he gave up two runs in 6 1/3 innings in his fifth start for the Diamondbacks since he underwent Tommy John surgery in March 2014.

In Game 2, the Rockies got four solid innings from starter Kyle Kendrick, then two scoreless innings from Christian Bergman. Scott Oberg (3-4) followed Bergman to the mound in the seventh, and he didn't retire any of the three batters he faced.

Oberg hit Gosselin with a 1-0 fastball to open the inning, then walked shortstop Chris Owings on seven pitches. Hill followed with a two-run double to the left-field corner that tied the game at 3 and finished the rookie reliever. In 50 games, Oberg has issued 22 walks and hit five batters in 47 innings. He has a 6.13 ERA.

Jairo Diaz relieved Oberg and gave up an opposite-field homer to Pollock, who hit a 1-2 slider over the right field fence. It was Pollock's 15th homer of the season, his second in the first three games of the series at Coors Field.

"I haven't seen the guy, but I knew he had a slider," Pollock said of Diaz. "I had it in my head; I wasn't really sitting on it. I hit it on the barrel. I think the good thing is I didn't stop my (swing) path. Yeah, it's probably an out in most parks. It definitely was a little bit helped from the Colorado air."

Arizona starter Rubby De La Rosa (12-6) gave up six hits and three runs in six innings. He did not allow a hit after third baseman Nolan Arenado's homer in the third, and he retired 10 of the final 11 batters he faced.

The Rockies responded to Goldschmidt's homer with two two-out runs in their half of the first. Shortstop Cristhian Adames, making his first start of the season for the Rockies after being recalled Tuesday, doubled with one out.

Adames scored on a single by Arenado, who took second on De La Rosa's comical balk -- he made a quick-pitch move and threw the ball to the backstop -- and scored on a double by first baseman Ben Paulsen.

"I don't know what I was thinking," De La Rosa said of his balk. "(Catcher Welington) Castillo told me, 'Did you see somebody going to steal home?' I don't know what happened."

De La Rosa said he immediately thought, "What am I doing?"

Josh Collmenter worked the final two innings to earn his first save this season and the second of his career.

Before the sweep, the Diamondbacks had lost three straight and seven of their past eight games. They improved to 34-33 on the road, while the Rockies' record at Coors Field fell to 28-38.

Arenado, who went 3-for-4 and finished a triple shy of the cycle, hit his National League-leading 32nd home run in the third, giving the Rockies a 3-1 lead.

"Always real tough losing doubleheaders," Arenado said. "Especially hard at this time of the year in September where people are tired. We battled, did the best we could. It just didn't work out."

Kendrick, who was reinstated from the disabled list for the start, worked four innings on 72 pitches and gave up three hits and one run.

Kendrick last pitched for Colorado on July 31 before missing a month with right shoulder inflammation. Having thrown 45 pitches one week ago in a simulated game, he was going to be limited to 70-75 pitches. He is still building arm strength, hence his departure after 72 pitches.

"He did a great job," Rockies manager Walt Weiss said, "and (Bergman) did his job getting us through the middle innings. And then we struggled late."

NOTES: Diamondbacks PH Aaron Hill left the game in the seventh as a precaution due to left hamstring soreness after hitting a two-run double. ... The triple play the Rockies turned in the ninth inning of the first game was the fourth triple play in franchise history and first since May 18, 2014, against San Diego. ... Diamondbacks RHPs Enrique Burgos and Matt Stites and INF Brandon Drury were recalled from Triple-A Reno. Drury made his major league debut in the first game of the doubleheader. ... Rockies 1B Wilin Rosario, RHP Miguel Castro, LHP Rex Brothers and INF Cristhian Adames were recalled from Triple-A Albuquerque. Castro took the loss in the opener during his Rockies debut. He was acquired from the Blue Jays in the six-player deal that sent SS Troy Tulowitzki to Toronto on July 27. ... Rockies RHP Kyle Kendrick (right shoulder inflammation) and LHP Boone Logan (left elbow inflammation) were reinstated from the disabled list.