DENVER (AP) — Chris Rusin has turned in a pair of gems at Coors Field this season. He was unable to duplicate that success against the Pittsburgh Pirates.

Rusin labored through four innings and the Colorado Rockies lost 6-3 Tuesday night to the Pirates.

Wilin Rosario homered and Charlie Blackmon had two hits and a stolen base, but the Rockies couldn't overcome a shaky start from Rusin.

"Today was just one of those days that I fell behind hitters and didn't make pitches when I needed to," Rusin said. "When I got behind in the count and had to force myself to throw a strike, I either gave up hits or the balls bleeded through. Things didn't fall my way."

Rusin (5-9), who has the only two complete-game victories for Colorado this year, wasn't nearly as sharp as he was in those wins. He walked four and allowed six runs on eight hits before leaving after 92 pitches.

"My fastball command was a problem," Rusin said. "I didn't have a secondary pitch I could throw for a strike."

Starling Marte drove in two runs and the Pirates closed in on their third straight playoff berth, reducing their magic number to one for securing at least an NL wild card. A victory Wednesday against the Rockies would clinch another trip to the postseason.

"Our guys have great presence. We're in the moment," Pittsburgh manager Clint Hurdle said. "We're not looking at yesterday, we're not looking at the team behind us. We're not looking at tomorrow or the team in front of us. We need to take care of our game."

Pittsburgh also kept pace with NL Central leader St. Louis. The Cardinals beat Cincinnati to maintain a four-game lead over the second-place Pirates.

Pittsburgh scored in each of the first four innings against Rusin to build a 6-3 lead.

Rosario's homer in the third cut it to 3-1, and RBI singles by Blackmon and Nolan Arenado made it 4-3 in the third.

Marte, who had an RBI double in the first, followed Aramis Ramirez's run-scoring triple in the fourth with a single off the bag at third to restore Pittsburgh's three-run lead.

"That is a pretty complete team that they have," Colorado manager Walt Weiss said.

The Rockies had a chance to cut into the lead when they had runners on first and third in the fourth, but J.A. Happ fanned Brandon Barnes and pinch-hitter Kyle Parker to get out of the jam.

Happ (6-2) left after walking Rosario in the sixth. The left-hander allowed three runs on seven hits and struck out eight.

Mark Melancon pitched the ninth for his 49th save, tops in the majors.

TRAINER'S ROOM

Pirates: Ramirez left in the sixth with tightness in his left groin. Hurdle said Ramirez got hurt rounding second on his triple in the fourth inning.

Rockies: Arenado exited with two outs in the top of the ninth. He hit his face on the dirt diving for an infield single by Jordy Mercer and was replaced by Daniel Descalso. Arenado passed a concussion test and will be evaluated Wednesday.

UP NEXT

Pirates: RHP Charlie Morton (9-8) makes his eighth career start against Colorado on Wednesday night. He is 2-2 with a 3.74 ERA overall against the Rockies but lost his only start against them this season.

Rockies: RHP Christian Bergman (3-0) steps in for ailing lefty Jorge De La Rosa. It will be Bergman's 28th appearance this season but only his second start. His last one was April 14 at San Francisco.