LaRoche hit a 2-run homer in Arizona's 5-run fourth inning and added a solo shot in the fifth that made the score 6-1. He also drove in two runs in the seventh when the Diamondbacks scored seven times.
Kelly Johnson and Chris Snyder each hit home runs and drove in three runs apiece for Arizona. Johnson had four hits and has hit home runs in five of his last seven games. The Arizona lead-off batter has nine home runs this season.
Ian Kennedy (1-1) took advantage of the support for his first win. He gave up six hits and five runs -- four earned -- over eight innings. Kosuke Fukudoma hit his first career grand slam for the Cubs in the eighth inning but Chicago was down 13-1 at the time.
Cubs starter Ted Lilly (1-1) allowed six runs on seven hits -- three being the home runs by LaRoche and Snyder -- over five innings.