DENVER (AP) -- Boosted by a couple of stellar rookie pitchers, the Colorado Rockies are on top of the National League in the final days of May.
German Marquez pitched into the sixth inning, Gerardo Parra hit a three-run homer and the Rockies beat the St. Louis Cardinals 8-4 on Sunday.
Parra finished with three hits as the Rockies won a series for the 12th time this season. They have dropped two and split two others.
"That's all we want to do, win series and keep going. It's our mindset," catcher Tony Wolters said. "We're not just saying it, we're doing it."
Colorado's longest winning streak this season is four games, a feat accomplished just twice this season. With Sunday's victory, the Rockies have won six of eight largely behind a young staff that has grown up quickly.
Marquez (4-2) allowed two runs and eight hits in 5 2/3 innings. He went 4-1 in May to help the Rockies' rookie starters finish 12-3 for the month for the most wins by rookie starting pitchers since Oakland got 11 in September 2009, according to Elias Sports Bureau.
"We've been pretty steady on the mound, we're playing sound and we have some guys that are hitting the ball," manager Bud Black said.
The Rockies have done it against good teams, too. They have won series against two other division leaders as well as two of their closest competitors in the NL West.
"We're on fire right now," Parra said. "The big point is we're getting great starting pitching."
Colorado built a 4-0 lead on Alexi Amarista's run-scoring groundout in the second and Parra's drive in the fourth off Lance Lynn (4-3).
"The pitch to Parra didn't move the way as much as I would like," Lynn said. "It spun a little bit on me and he put a good swing on it."
St. Louis got back into it on homers from Jedd Gyorko and Greg Garcia in the sixth. Tommy Pham's solo shot to center off Chris Rusin in the seventh made it 4-3.
Colorado tacked on four runs in the eighth off Matt Bowman, two on Wolters' single before John Brebbia got the final out in his major league debut.
Cardinals: 2B Kolten Wong was placed on the 10-day disabled list with a left elbow strain, retroactive to Saturday. Wong was a late scratch from Saturday's lineup.
Paul DeJong's first swing in the major leagues was a memorable one. DeJong, called up to take Wong's roster spot, hit a 1-0 pitch off Greg Holland into the seats in left field in the ninth with his parents in the stands.
He is the ninth player in St. Louis history to homer in his first career at-bat and the first since pitcher Mark Worrell did it on June 5, 2008.
"I was just looking for a fastball in after a first-pitch ball," DeJong said. "He slipped me something down in an area I wanted and put a pretty good swing on it."
ROAD TO RECOVERY
Rockies right-hander Jon Gray, on the disabled list since April 14 with a stress fracture in his left foot, threw for the first time without a boot. Black said Gray threw 30 to 35 pitches Sunday morning and will do more baseball activities this week.
"Most of the work he's going to do is strengthening the leg," Black said. "There's been things he hasn't been able to do because he's in that boot, strength-training things that all players need."
Cardinals: RHP Mike Leake (5-2, 1.91 ERA) will make his second straight start against the Los Angeles Dodgers on Monday. Leake, who leads the NL in ERA, allowed one run in eight innings in a 6-1 win over the Dodgers on Wednesday night.
Rockies: RHP Tyler Chatwood (4-6, 4.50 ERA) will open a four-game, home-and-home series with Seattle on Monday. Chatwood has earned a decision in each of his 10 starts this season..