LOS ANGELES -- The Los Angeles Dodgers are already locked into the No. 2 seed in the NL playoffs.
Yet, they keep on winning on the road to the postseason.
The Dodgers (93-68) have won four straight, including an NL West-clinching victory over San Francisco on Wednesday.
Colorado's bullpen retired 18 straight, a stretch that spanned from the sixth inning until the 12th, but couldn't turn that into a win.
Van Slyke singled with one out, advanced to second when Tim Federowicz was hit by a pitch, stole third, and came home on Morales' wild pitch.
"Scott Van Slyke single-handedly won the game for us right there," catcher A.J. Ellis said. "That was a big base hit. We hadn't had a baserunner in quite some time. Then for him to show off not just his speed, but his baseball savvy.
"Give him a lot of credit for baseball IQ and knowing what was needed for us to get off that field."
Rookie Carlos Frias (1-1) pitched three scoreless innings for Los Angeles for his first major league win.
"Carlos was amazing," Ellis said. "Giving us three innings like that, he kept giving us chances to come back and make something happen."
Morales (6-9) took the loss for Colorado (66-95), which has dropped three straight.
The Rockies took a 2-1 lead into the fifth inning, but the Dodgers erased it with a four-run spurt that knocked starter Eddie Butler from the game.
"(Butler) looked pretty sharp early, but it got away from him in the fifth," Rockies manager Walt Weiss said. "I felt like he threw some good sinkers, but I think he started to catch a lot of the plate in the fifth inning and he got nicked up there."
Los Angeles rapped out four hits in the inning, including Van Slyke's tying RBI single and Matt Kemp's go-ahead RBI double.
Dodgers manager Don Mattingly subbed often, and by the top of the sixth, eight of Los Angeles' nine starters had been replaced -- including pitcher Dan Haren.
"There's still (postseason) roster spots open," Mattingly said. "We're kind of throwing guys out in different spots and seeing what we get."
"Paulsen has made quite an impression," Weiss said. "Good hitter. Really pretty swing. He's done a nice job."
Haren took a no-decision but continued a recent hot stretch with a solid outing. He pitched five innings, allowed two runs and six hits, walked none and struck out four.
He has a 2.09 ERA over his last seven starts, dating to Aug. 26.
Haren wasn't available after the game but left a sign on his locker for media that read: "I felt good. I'm ready for the playoffs."
Butler, making his third career start, gave up five runs and eight hits in 4 2/3 innings for Colorado.
Dodgers: 2B Dee Gordon was removed in the second inning due to right hip irritation. His removal was characterized as a precaution by team staff and he is day to day. ... LHP Hyun-Jin Ryu (left shoulder inflammation) didn't report any pain after throwing off a mound Friday. He will throw a full bullpen session Sunday.
Rockies: 2B DJ LeMahieu (sprained left knee) will have an MRI on Monday. He was injured while diving for a ball in the series opener.
Dodgers: RHP Zack Greinke (16-8, 2.74) looks to remain unbeaten since Aug. 9. He is 4-0 with a 2.40 ERA in his last seven starts.
Rockies: RHP Christian Bergman (3-4, 5.29) wraps up his rookie season. Bergman, 26, has won three of his last four decisions.