Derrek Lee found his power stroke quickly this year.\nLee hit a tie-breaking homer in the seventh, Carlos Zambrano struck out seven in seven innings and the Chicago Cubs beat the Houston Astros \n3-2 Sunday.\nLee connected against Oscar Villarreal (0-2) for his third homer of the season. The Cubs first baseman finished 2-for-3 with a walk, and his one out was a long fly to deep center. He didn’t hit his first homer last season until the 21st game and finished the season with only 22.\nThe Astros had tied it when Miguel Tejada hit his first homer with Houston leading off the seventh.\nSlumping Alfonso Soriano homered and made a great throw for the Cubs, and Zambrano (1-0) avoided the cramping that forced him out of the season opener. He allowed two runs and seven hits with \nno walks.\nKerry Wood pitched a perfect ninth for his third save in as many chances, striking out Tejada to end it.\nSoriano was 1-for-24 this season when he lifted a 1-1 pitch from Brandon Backe over the left-field wall in the fifth to put the Cubs ahead 2-1.\nHe also bailed Zambrano out of a first-inning predicament by catching Carlos Lee’s fly ball and throwing out speedy Michael Bourn at the plate for an inning-ending double play.\nZambrano was forced to leave his opening-day start in the seventh with a forearm cramp. Also bothered by cramping last season, he’d been advised by the team’s training staff to cut back on his pregame caffeine intake and drink more water. He threw 106 pitches against Houston.\nBourn led off with a single and made it to third on a double by Hunter Pence. Zambrano fanned Darin Erstad before Carlos Lee lifted a fly to left and Soriano made a perfect throw. Soriano had 19 outfield assists last season.\nBacke went six innings, giving up six hits and two runs with three walks and \nseven strikeouts.\nZambrano’s bases-loaded double-play grounder put the Cubs ahead 1-0 in the second. The Astros tied it when Erstad’s two-out single in the third scored Backe, who led off with a fly ball double to right that got behind \nKosuke Fukudome.\nThe Cubs loaded the bases with one out in the fifth, but Backe escaped by striking out Mark DeRosa and getting Ryan Theriot to ground to shortstop.