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04/29/10 6:49 PM ET

LaRoche's two blasts power D-backs

Johnson hits National League-leading ninth homer in win

CHICAGO -- For the second successive day, the D-backs scored in double digits.

The difference Thursday was they got the pitching to go with it, which led to a comfortable 13-5 win over the Cubs in front of 36,850 at Wrigley Field.

Arizona has now won four of its past five games and is 3-1 on this three-city, 11-game road trip.

The D-backs had to go 10 innings to beat the Rockies, 12-11, on Wednesday.

"Obviously that's a lot of runs for two days," said first baseman Adam LaRoche, whose father Dave pitched for the Cubs during his 14-year career. "But I think we're showing some signs of what we can do throughout the whole lineup."

The wind was blowing out at Wrigley, but early on, neither offense did much, with the Cubs taking a 1-0 lead in the third on an RBI single by Ryan Theriot.

It didn't last long.

The D-backs sent nine men to the plate in the fourth as they scored five runs.

LaRoche got things started when he made Ted Lilly pay for back-to-back walks to open the frame with a three-run homer to center. Chris Snyder later added a two-run homer of his own.

It was the first of two homers on the day for LaRoche, who went 3-for-4 with a double to raise his average to .299. Suddenly, the man who has struggled in just about every April of his seven-year big league career has four homers and 17 RBIs.

"I'm 150 points above my average," LaRoche said. "I haven't changed a thing, never will. You get some balls to fall, you get your confidence up. I wish I had an answer for you. It's a lot more fun doing this than hitting a buck 50."

Speaking of power, second baseman Kelly Johnson, who like LaRoche was signed as a free agent, helped the D-backs tack on seven runs in the seventh inning with a three-run homer of his own.

Johnson, who collected four hits and is batting .320, is leading the National League in homers with nine.

"If they go out or whatever, that's cool, but I'm not worried about it," Johnson said. "I just want to keep getting pitches to hit, have good at-bats and hit it hard. That's all I care about."

All the offense proved to be more than enough support for D-backs starter Ian Kennedy.

"It's nice to have those leads," Kennedy said. "You know you can go after guys more. It makes you feel more comfortable when you have a big lead like that."

The right-hander, who was making his first appearance at the Friendly Confines, was dazzling for seven innings as he held the Cubs to just one run.

"Their pitcher did a wonderful job," Theriot said. "This dude was throwing every pitch in his repertoire for strikes. You really couldn't look for a certain pitch off of him in a certain count. You don't see too many pitchers who throw righties an inside changeup."

With their bullpen taxed, the D-backs needed Kennedy to go deep in the game, and he did not disappoint, even if the eighth inning did take a little luster off the outing.

In that frame, Kennedy walked the leadoff batter, another reached on an error and Theriot singled to load the bases. Kosuke Fukudome unloaded them when he hit a first-pitch fastball just over the wall in left for a grand slam.

"I tried to throw a two-seamer, and he was looking for a fastball, obviously," Kennedy said of the pitch to Fukudome.

Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.