DENVER -- Colorado Rockies rookie third baseman Nolan Arenado has shown he likes the challenge of coming through in a key moment.
He did it again Sunday with a two-out double in the seventh that helped give the Rockies a 3-2 win over the Pittsburgh Pirates.
Rockies closer Rex Brothers survived a ninth-inning scare for the second straight game.
The series sweep gave the Rockies their first three-game winning streak since May 21-24. The loss cut the Pirates' lead over the St. Louis Cardinals to two games in the National League Central. The Pirates and Cardinals begin a three-game series Tuesday at St. Louis.
The Rockies trailed the Pirates 2-0 before scoring single runs in the third and sixth, setting the stage for Arenado's clutch hit.
With two out in the seventh, Wilin Rosario blooped a single to short center field. Arenado followed with an opposite-field double to right off Bryan Morris, ending the scoreless streak by Pirates relievers at 18 2/3 innings.
Arenado's double, his 20th of the season, extended his career-high hitting streak to eight games and gave him at least one hit in 18 of his past 20 games.
Closer Rex Brothers, who threw 27 pitches Saturday night and 12 on Friday night, came on in the ninth and gave up a leadoff single to Neil Walker. Brothers struck out pinch hitter Russell Martin. But Tony Sanchez's double to right-center moved Walker to third.
With the infield drawn in, pinch hitter Jordy Mercer lined out to Arenado. Brothers intentionally walked pinch hitter Gabby Sanchez and got Alex Presley to pop out to Arenado on Brothers' 17th pitch to pick up his 10th save.
Making his third major league start and his Coors Field debut, Chad Bettis held the Pirates to two runs and four hits in six innings.
Pittsburgh starter Jeff Locke worked 5 2/3 innings and gave up three hits, the last a single by Charlie Blackmon that put runners on first and second.
Tony Watson came on to face pinch hitter Corey Dickerson and got him to hit a slow grounder to third baseman Pedro Alvarez. But he overthrew first base, allowing Yorvit Torrealba to score and tie the game at 2-2.
The Rockies couldn't capitalize on shortstop Clint Barmes' error in the fifth and left the bases loaded when Locke got Rosario to ground out.
Bettis gave up Pedro Alvarez's 28th home run, leading off the second, and allowed a run in the third on Andrew McCutchen's squib single to Bettis with two out. The hit scored Barmes, who led off with a double and was sacrificed to third.
The Rockies scored a run without the benefit of a hit in the third. Locke hit leadoff hitter Blackmon with a pitch. He stole second, moved to third on a balk and scored on LeMahieu's sacrifice fly.
Notes: Rockies C Rosario made his second career start and third appearance at first base where he had played 10 innings prior to Sunday. He started there Sept. 20, 2012, at San Francisco and played two innings at first base this season on July 31 at Atlanta...Pirates LF Starling Marte pinch ran in the ninth. He was not in the lineup after getting hit with a pitch and suffering a left hand contusion in the seventh inning Saturday night...Alvarez was spiked and suffered a laceration on his left index finger Saturday night but was in the Pittsburgh lineup Sunday...With the Pirates off Monday, rookie RHP Gerrit Cole will have his next start pushed back to Friday against Arizona as the Pirates monitor his innings.