Coming off a dramatic ninth-inning victory, the A's look to sweep this three-game set Sunday with a sixth consecutive home win over an Astros team that's trying to avoid a seventh straight defeat.Less than 24 hours after hitting four homers during an 11-3 rout of Houston (5-13), Oakland scored three times in the ninth Saturday to win 4-3. Alberto Callaspo delivered a tying hit and Josh Reddick's RBI single sent the A's (12-5) to their 10th win in 12 games."We're off to a good start this year of really grinding out those last inning at-bats and making it tough on the other guys, never making it easy on them," said shortstop Jed Lowrie, who led off the ninth with a home run.Oakland is 22-5 all-time against the Astros.Reddick is 6 for 9 with three RBIs in the set after going 4 for 41 with one RBI in his first 12 games."It's a great turnaround, a great feeling to be back in the box with some confidence," he said.Callaspo has six of his 10 RBIs in the last four contests while teammate Yoenis Cespedes is batting .421 during a 14-game hitting streak against the Astros, who have scored 13 runs during their six-game slide.Oakland has won all three outings by scheduled starter Jesse Chavez (0-0, 1.35 ERA). The right-hander struck out nine and lasted seven innings in each of his last two, most recently Monday when he allowed two runs during a 3-2 win over the Los Angeles Angels -- his first 2014 start that didn't end in extra innings.Chavez, who made two starts over his first six seasons, is making the most of his time in the rotation with Jarrod Parker and A.J. Griffin injured."That's exactly what we've seen," manager Bob Melvin told the Athletics' official website. "That's the way he's been pitching for us, even in spring training."Chavez has a 0.92 ERA in 15 relief appearances against Houston, pitching 6 1/3 scoreless innings last season.Astros shortstop Jonathan Villar is 4 for 7 with a homer in the series after going 1 for 24 in his previous nine games. He's hit .429 (9 for 21) in his last five against Oakland.The Astros hand the ball to Brad Peacock (0-1, 7.45), who makes his first start of the year after replacing Lucas Harrell in the rotation. Peacock spent the 2012 season in the Oakland organization but never pitched for the A's before he was traded to Houston in a deal that brought Lowrie to the East Bay.The right-hander began last season 1/3 with an 8.44 ERA in five starts, but after two trips to the minors and time in the bullpen, he went 4-3 with a 3.64 ERA in his final nine starts."Peacock is the next in line, and I think he's going to pick up where he finished last year in September," general manager Jeff Luhnow told the Astros' official website.He went 1-1 with a 4.02 ERA in three starts against Oakland in 2013. Coco Crisp and Eric Sogard are both 4 for 7 when facing Peacock, while Cespedes is 1 for 5 with four strikeouts and Lowrie is hitless in seven at-bats.