ST. LOUIS -- Chris Rusin had a simple game plan going into Friday night's start.
"Don't let the heart of their order beat me," he said.
It turned out no one was beating Rusin. The young left-hander combined with four relievers for the Chicago Cubs' first shutout win in St. Louis in 16 years, a 3-0 verdict at Busch Stadium.
Rusin (2-1) scattered seven hits in six innings, then saw the offense spring to life by scoring three runs with two outs in the top of the seventh.
From there, the bullpen sealed it with hitless work in the last three innings. Kevin Gregg pitched the ninth for his 24th save as Chicago (51-64) won for just the third time in 12 games.
Cubs manager Dale Sveum said it all started with Rusin.
"He's been pitching really well," Sveum said. "All he has to do is throw strikes because his ball moves so much. He's been keeping the ball down. Tonight, he made pitches when he had to."
Rusin escaped jams in the second and fourth innings despite allowing two-out doubles to Jon Jay. Each time, he intentionally walked Pete Kozma and then retired pitcher Lance Lynn to quell the threats.
In the fifth, after Matt Holliday's two-out single moved David Freese to third, Rusin jammed Matt Adams with a 1-1 fastball and got a comebacker to end the inning.
"I really wanted to get ahead of the hitters because I'm not overpowering and if I'm not ahead, it can be trouble," Rusin said. "I don't think too much. I just want to give the team a chance to win."
Lynn (13-6) did the same for the Cardinals, allowing three hits and fanning five in 6 2/3 innings, but was ultimately undone by wildness and the Cubs' ability to produce the clutch hits that St. Louis (66-49) couldn't.
In the seventh, Lynn walked leadoff man Welington Castillo and then gave a one-out free pass to Darwin Barney, Lynn's fifth of the night. Pinch-hitter Logan Watkins struck out, but Junior Lake lashed a single to center and Castillo beat Jay's throw home for the first run.
"The problem was going 3-1 to a guy who's swinging the bat really well," Lynn said of Lake's hit.
After plunking Cole Gillespie -- the second batter he hit in the game -- Lynn departed so that lefty specialist Randy Choate could face lefty-swinging Anthony Rizzo. But the Chicago first baseman won that matchup, grounding a two-run single to center that capped the scoring.
The Cardinals lost for the 12th time in 16 games and stayed four games behind National League Central leader Pittsburgh, a 10-1 loser in Colorado. Their frustration showed in the bottom of the ninth.
Pinch-hitter Daniel Descalso took a called third strike, argued at the plate and then kept arguing from the dugout. Plate umpire David Rackley ran him and then booted manager Mike Matheny.
"You think you need to do more, but that's when you get in trouble," Lynn said of a skid that has cost St. Louis 6 1/2 games in the standings since July 25. "With the guys we have in this locker room, we just need to do what we're capable of and we'll be fine."
NOTES: Chicago C Dioner Navarro (right ankle sprain) wasn't with the team on Friday while he had his injury checked out. Navarro got good news, learning that he won't have to go on the disabled list after his home plate collision on Wednesday with Philadelphia's Chase Utley. ... Cubs RHP Matt Guerrier has been diagnosed with a flexor mass in his right elbow and will have to make a decision at some point about surgery. The team doesn't believe he'll have to undergo a Tommy John procedure, though. ... St. Louis RHP Carlos Martinez became the team's fifth rookie to start a game on Thursday night. Rookies have accounted for 36 of the Cardinals' 115 starts, a number that will go up to 37 on Saturday night when RHP Michael Wacha is called up from Memphis to start.