Cain takes the ball Wednesday afternoon at Minute Maid Park, where the Giants look to sweep the season-opening series and spoil Brett Myers' Houston Astros debut.After two-time reigning NL Cy Young Award winner Tim Lincecum allowed four hits in seven scoreless innings of Monday's 5-2 season-opening victory, veteran lefty Barry Zito struck out five and surrendered three hits over six innings of a 3-0 win Tuesday."It's big to come out and win a series in the second day and we can go out and get that sweep (Wednesday)," Zito said.San Francisco hasn't swept its first series since 2003 against San Diego, but the hard-throwing Cain could change that. Coming off his first All-Star appearance and a career-best 14-8 record and 2.89 ERA in 2009, the 25-year-old right-hander is excited for the new season after signing a three-year extension last month."It just shows appreciation for the things I've done, and the way they run the organization," said Cain, who will earn a reported $27.25 million over the length of his deal. "It shows that we can do something to benefit both sides."Cain has become a young workhorse for the Giants over the last four seasons, pitching at least 190 2/3 innings each year. He matched a career high with 217 2/3 last season, and tied for the NL lead with four complete games.Cain is 1-2 with a 3.52 ERA in four career appearances -- three starts -- against the Astros.Myers is looking to get his career back on track after an injury-plagued season with Philadelphia. Signed to a one-year deal in January after spending his first eight seasons with the Phillies, the right-hander missed more than three months last year with a torn labrum in his right hip. He finished 4-3, but posted a career-worst 4.84 ERA while splitting time between the starting rotation and bullpen.Houston does not appear concerned."He got a clean bill of health in all respects, the hip, the shoulder, everything checks out fine," said Astros team president Tal Smith. "He's a big, strong guy. He's been a workhorse and there's no reason why he can't continue."Myers strained his groin March 25, but said he didn't feel any effects of the injury last Friday after throwing 82 pitches in his final spring training outing.With a .194 team batting average and 16 strikeouts through two games, the Astros may sorely need a solid outing from Myers."This is not the way we should be playing," said right fielder Hunter Pence, who is hitless in eight at-bats. "We just have to start scoring runs and start hitting. Hitting is contagious and once the first guy hits, we all will."Astros left fielder Carlos Lee went 0 for 4 Tuesday, but is 5 for 8 with a homer and three RBIs lifetime versus Cain.Houston is trying to avoid its second season-opening sweep in four years. The Astros dropped three straight home games to Pittsburgh to open 2007.