Overshadowed by his masterpiece, however, was another strong offensive showing by the Giants against a Houston starting pitcher.Going for a sweep, San Francisco could be poised for another big game Thursday when it faces Wandy Rodriguez, who has been knocked around regularly over the last month.Cain made history Wednesday, throwing the majors' 22nd perfect game and the first in franchise history for the Giants (36-27).He made things look easy at times by striking out a career-high 14, but also benefited from a couple of outstanding plays by his corner outfielders. After left fielder Melky Cabrera made a leaping catch at the wall on Chris Snyder's flyball in the sixth inning, right fielder Gregor Blanco made a diving catch on the warning track to rob Jordan Schafer an inning later."Those were unbelievable catches," Cain said. "I mean that right there, that changes the whole thing."The offense also gave him plenty of breathing room in the 10-0 win. The Giants matched a season high with 15 hits and reached double digits in runs for only the second time, winning for the 12th time in their last 16 games and moving within 3 1/2 games of NL West-leading Los Angeles.Blanco, Cabrera and Brandon Belt each hit a two-run homer, while Pablo Sandoval added three hits and two RBIs. Almost all the damage came off starter J.A. Happ, who was battered for eight runs and 11 hits in 3 1/3 innings."The guys did a great job making it, in a way, kind of relaxing, because they were able to get on the board early," Cain said.Happ lasted just as long as Tuesday's starter Bud Norris, who yielded three runs, three hits and three walks before leaving with his left knee hurting. The Giants, 9-3 against the Astros at AT&T Park since 2009, went on to win 6-3.Rodriguez (5-4, 3.27 ERA) hasn't allowed an earned run over 14 innings in winning his last two starts against San Francisco, but he hasn't been nearly as sharp lately.Houston's opening day starter has surrendered at least eight hits in each of his last five outings, with opponents batting .368 in that stretch.He managed to limit the damage Friday against the White Sox after giving up 16 runs in his previous two starts. The left-hander yielded nine hits and a walk in 5 1/3 innings at Chicago, but only three came around to score in an 8-3 victory.Rodriguez doesn't have a lot of experience against many San Francisco regulars, but Cabrera is 2 for 4 against him with a pair of doubles. Cabrera, who leads the majors with a .367 average, is 4 for 9 in this series after missing the previous three games with a sore right hamstring.Barry Zito (5-3, 3.24) has the impossible task of following up Cain's gem.He'd settle for a bounce-back performance after giving up four runs and nine hits -- including two homers -- in six innings of Friday's 5-0 loss to Texas. Zito had a 1.17 ERA in winning his previous two outings and could fare better against an Astros team that ranks last in the NL with a .219 average versus left-handers.Chris Johnson is hitting .280, but is at .209 against lefties. Jed Lowrie, .279 overall, is batting .204 versus southpaws.Zito is 3-2 with a 4.54 ERA in six career starts against the Astros but hasn't faced them since 2010.