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Neil Walker just kept coming around third and with a hard slide he capped a two-run rally in the ninth inning against Cubs closer Carlos Marmol that sent the Pittsburgh Pirates to a 5-4 victory Sunday.

What a way to kick off the season.

The Pirates took two of three against Chicago in the three-game set. They won only four road series last year — two at Wrigley Field.

"It goes back to the aggressive baserunning trend, try to be smart and try to be aggressive," Pirates manager Clint Hurdle said. "Nick (Leyva) is a very aggressive third base coach and Neil plays the game that way when he's on the bases. Once he saw the play develop from second base, he knew there was a very good shot he was going to pull something off and he did."

With the Cubs leading 4-3, Pittsburgh's Garrett Jones led off the ninth with a walk against Marmol (0-1) and Walker singled before Lyle Overbay sacrificed to put runners at second and third.

Pedro Alvarez hit a slow roller to shortstop Starlin Castro. As Jones raced home, Castro's throw to first pulled Carlos Pena off the bag and Walker rounded third. Pena threw to the plate, but Walker made a hard slide under Cubs catcher Geovany Soto to score the go-ahead run.

"My goal was just to score," Walker said. "I knew (Castro) had a tough play and if he comes up and picks that ball clean and makes a good throw to first, he still has to make a really good throw to home to get me. ... I don't know if he (Leyva) tried to hold me or not, but my goal was to be at home and fortunately I was and it ended up being a big play."

Jeff Karstens (1-0) pitched a scoreless eighth for the win and Joel Hanrahan the ninth for his second save, getting Marlon Byrd to hit into a game-ending double play after an error by Pirates shortstop Ronny Cedeno helped the Cubs put runners at first and third.

"A tough one for sure," Chicago manager Mike Quade said.

"Carlos (Pena) did a heck of a job fielding it and nearly throwing the guy out at home. Seems like one of those days where there was a lot of stuff."

Pittsburgh's rally prevented Matt Garza from getting a victory in his Cubs debut. He left with a 4-3 lead after allowing 12 singles and striking out 12 in seven innings.

Both the hits allowed and strikeouts were career highs for Garza.

"Even though the 12 singles are annoying, I just kept telling myself to get to the next pitch and keep attacking," he said.

All 16 of the Pirates' hits were singles.

Garza, who struggled this spring, was the Cubs' major offseason acquisition, coming over in a trade from Tampa Bay after winning 15 games last season for the Rays in the tough AL East. He did not walk a batter.

Alfonso Soriano homered in the sixth against Pirates starter Ross Ohlendorf to put Chicago up 4-3. The Cubs thought they had preserved that lead when right fielder Tyler Colvin made a strong throw to cut down a potential run in the eighth.

Ohlendorf gave up eight hits in six innings, including a tying double to Pena in the fourth when his high drive hit the ivy in right field and Jones couldn't make a leaping catch as a fan's drink splashed over the wall.

The fan was apparently trying to get ready for a catch when he lost his drink. He was not ejected but relocated to another section, a Cubs spokesman said.

Jones said the liquid didn't interfere with his attempt to catch the ball.

"Not really. The ball was a little above my glove," he said. "It kind of came down and hit me in the head and the mouth a little bit, but it tasted good."

Hurdle went out to question the umpires for several minutes about a potential interference call before returning to the dugout. Ohlendorf settled down, got two outs and after an intentional walk to Colvin loaded the bases, retired Garza on a roller to first to end the inning.

Lyle Overbay had an RBI single in the fifth to put the Pirates up 3-2. But Castro's leadoff triple — his first of two three-baggers on the day after being moved into the leadoff role — and a sacrifice fly by Darwin Barney tied it in the bottom half.

Pittsburgh loaded the bases against Kerry Wood in the eighth but Colvin caught Jose Tabata's medium fly and made a perfect throw to the plate to nail Jason Jaramillo for a double play to end the inning.

NOTES: Quade said Carlos Zambrano was OK on Sunday, a day after the right-hander had to leave in the seventh inning with a hand cramp. Zambrano is expected to make his next start Friday when the Cubs begin a series in Milwaukee. Zambrano has had cramping issues in the past and had to start drinking more water while increasing his potassium intake. ... Quade said Castro would return to second in the order Monday against the Diamondbacks. ... Pirates CF Andrew McCutchen was scratched with a stiff neck after making a diving attempt Saturday at a ball off the bat of Zambrano.