With Jose Altuve's status unclear, Martinez will try to continue his impressive production as the Astros go for a fourth win in five tries Wednesday night against the San Diego Padres.A strained right hamstring has sidelined Altuve for the first half of this four-game series with San Diego (27-48). The second baseman is Houston's leader with a .309 average, but Martinez is doing his part to fill the void for the Astros (31-43).The left fielder is hitting .333 in the first eight of this 10-game homestand, and he's connected for three homers while going 5 for 16 with eight RBIs to spur Houston's 3-1 run."He's getting back into that hitter that we all saw last year and that's nice to see," manager Brad Mills said. "He's on a little roll here and we surely hope that can continue."Mills and Martinez had a talk and watched some video of him at the plate at the beginning of this homestand in an attempt to improve his approach. Martinez said he's feeling good and not missing his pitches lately."You want to make a difference -- anything you can do to help the team win," said Martinez, who is batting .235 with 10 homers and 45 RBIs overall.His production has keyed the Astros' recent offensive breakthrough. They're hitting .294 with 10 homers in four games after compiling a .225 average with five home runs while losing six of the previous seven.Lucas Harrell (6-6, 4.77 ERA) is slated to get the ball against the Padres for the first time as he tries to continue pitching well at home.The right-hander is 4-1 with a 2.48 ERA in six starts there, though the loss came in hard-luck fashion Friday. He struck out a career-high nine over seven innings while yielding one run and two hits in a 2-0 defeat to Cleveland."The location of his fastball was pretty impressive," Mills said. "That was the biggest thing. He stayed aggressive with his fastball. He was making really good pitches on it."The Padres are expected to turn to Clayton Richard (5-7, 3.95), who is hoping to carry his interleague success back against NL opponents.The left-hander had a 1.69 ERA in winning his last three starts. All of those came against the AL, with two on the road.He's 0-4 with a 6.57 ERA in six starts away from home against NL teams.Richard's latest outing was more memorable at the plate than on the mound, as he went 2 for 2 with a double and three RBIs Friday as the Padres rallied for a 9-5 win over Seattle.Richard was a reason the comeback was needed, as he allowed four runs in the first three innings before settling down and yielding one more in the next 3 2-3."If we're winning, that's the fun," Richard told the team's official website. "If we're winning, then I don't care how it happens."In his lone start against Houston, Richard was tagged for six runs and seven hits in 5 1/3 innings April 17, 2011, at Minute Maid Park. He didn't get a decision in San Diego's 8-6 win.