The Cardinals look to complete a three-game sweep with an eighth straight win over the lowly Astros on Thursday at Busch Stadium.David Freese and Yadier Molina each hit their 20th home runs, and Lance Lynn threw 6 1/3 innings as St. Louis (79-70) won its third in a row, 5-0 over Houston on Wednesday.The reigning World Series champion Cardinals hold a two-game lead over the Los Angeles Dodgers and 2 1/2-game advantage over surging Milwaukee in the race for the NL's final wild-card berth.St. Louis has been able to remain in that position by continuing its dominance over Houston (48-101), which has been outscored 51-13 during a seven-game skid against the Cardinals that dates to a 9-8 home win June 5. St. Louis has outscored Houston 33-8 while winning all five games between the teams at Busch Stadium in 2012."They have some guys that can hit the ball and you just want to work hard and try and get through the game," losing pitcher Lucas Harrell said.Molina, 4 for 6 in the series, is batting .412 (14 for 34) against the Astros this season. Freese is 4 for 24 in his last seven games but is hitting .393 (11 for 28) with four homers and 13 RBIs in his last seven versus Houston.Scheduled St. Louis starter Jaime Garcia (4-7, 4.24 ERA) is 2-2 with a 2.63 ERA in seven home starts this season but 0-5 with an 8.10 ERA in seven career outings versus Houston. He's yielded 12 runs and walked six in eight innings while going 0-2 against the Astros at Minute Maid Park in 2012.The left-hander's most recent outing also came on the road Saturday when he allowed one earned run and three hits in six innings while not factoring in the decision of a 4-3 loss at Los Angeles.While the Cardinals hope Garcia can change his luck against the Astros, the Cardinals might have a good chance to complete the sweep against scheduled starter Bud Norris (5-12, 4.93).The right-hander is 0-11 with a 6.04 ERA in 17 starts since beating the Chicago Cubs on May 21. He is 1-2 with a 3.50 ERA versus St. Louis this season, with both defeats coming during his current winless stretch.Norris had allowed one run over 12 2/3 innings of his previous two starts before he gave up five in 5 1/3 innings of a 5-1 loss at Cincinnati in his most recent Sept. 8."I'm trying to leave it all on the field," said Norris, who has been given some extended rest in order to allow a blister on his pitching hand to heel.Rookie third baseman Brandon Laird had two of the five hits Wednesday for Houston, which has been held to one run and 12 hits in the first two games of the set.Astros outfielder Justin Maxwell is 0 for 7 with five strikeouts in the series but 4 for 6 with two doubles and a homer against Garcia.