Jason Castro and Chris Johnson each smacked three-run homers to back Bud Norris\' strong outing Monday in Houston\'s 8-4 win over the Chicago Cubs. Castro\'s shot put the Astros ahead 3-0 in the second inning and Johnson\'s blast in the next frame put the contest away for Houston. Jed Lowrie went 3-for-4 with an RBI and Carlos Lee added two hits, including a run-scoring single, as the Astros took the first of a three-game set at Minute Maid Park. Norris (5-1) won his fourth straight start with seven shutout innings, working around five hits and three walks while striking out eight. Cubs starter Matt Garza (2-2) was pounded for seven runs on five hits in a three-inning effort. Blake Lalli drove in a pair of runs for Chicago, which fell for the seventh straight time.