Beaten in Thursday's opener, the Rockies bounced back with a 6-3 win in game two on Friday and narrowed their deficit in the National League's West Division to 6 1/2 games behind the front-running San Diego Padres.
Colorado trails the league's incumbent wild card leaders, the San Francisco Giants, by 5 1/2 games.
On Friday, Carlos Gonzalez went 3-for-4 with a solo home run, two RBI and two runs scored for the Rockies.
Troy Tulowitzki finished 3-for-5 with an RBI while Dexter Fowler scored twice and drove in a run for the Rockies, who have won six of their last eight. Jason Hammel (8-6) went six innings and was charged with three runs on three hits with two walks and two strikeouts.
Zach Duke was tagged for three runs on 10 hits with five strikeouts over six innings in the start. Chan Ho Park (0-1), in his Pittsburgh debut, was handed the loss for giving up the go-ahead run in the seventh.
Mexican-born southpaw Jorge De La Rosa takes the mound for the visitors in search of a second straight win.
The 29-year-old, who won 16 games last season, picked up win No. 4 of an injury-riddled 2010 on Aug. 1 when he allowed eight hits and three runs in 6 2/3 innings against the Chicago Cubs.
He'd taken loss No. 3 one start earlier when he dropped a 4-2 verdict to the Pirates in Denver.
That loss dropped De La Rosa, a former reliever, to 3-2 in nine career meetings with the Pirates -- five starts -- with a 3.90 earned run average in 32 1/3 innings.
For Pittsburgh, righty Ross Ohlendorf again looks for his initial win since July 2.
The former Arizona Diamondbacks draft choice was a 2-0 winner over Philadelphia that day, but has since gone 0-3 in five starts though he's allowed three runs or less four times.
He took a 4-0 defeat against Cincinnati in his last start on Aug. 2, one outing after he'd lasted just two-thirds of an inning against the Rockies before being hit in the right side of the face by a Tulowitzki line drive.
He was checked at a hospital and returned to Coors Field before the end of that game, in which the Pirates won by a 6-2 count.
Ohlendorf is 1-1 in three career starts against Colorado with a 6.94 ERA.
Though the Pirates took two of three in Colorado from July 27-29, the Rockies have still won seven of the last 11 meetings overall.