Lance Lynn will look to help the Cardinals win three straight for the first time in nearly a month Wednesday night against the major league-worst Astros.St. Louis increased its lead over the Los Angeles Dodgers for the second NL wild card to 1 1/2 games with a 4-1 win Tuesday. The Dodgers were idle because of a rainout and are scheduled to play a doubleheader at Washington on Wednesday.The Cardinals (78-70) extended their tenuous lead after Kyle Lohse pitched seven scoreless innings and added an RBI double in the fifth.St. Louis had lost 13 of 19 before Tuesday's win -- its sixth straight over the Astros, who suffered their 100th loss of the season.Looking to win seven in a row against the Astros in a single season for the first time since 1996, the Cardinals seek their first three-game win streak overall since a four-game run from Aug. 21-24.Lynn (15-7, 3.95 ERA) will try to win a second consecutive start after making six straight relief appearances. Starting in place of the injured Jake Westbrook, Lynn gave up one run and struck out seven in six innings of a 2-1 victory over the Dodgers on Thursday."That's one of the best starts he's had this season," manager Mike Matheny said. "It just says volumes about his makeup and his stuff. It was a tough transition to the bullpen, and some guys handle it better than others."Lynn's return to the rotation could be brief, however. Westbrook, who is out with a right oblique strain, told the team's official website he thinks he could return as soon as next week. Chris Carpenter is also scheduled to make his season debut Friday.For now, Lynn hopes to continue taking advantage of the opportunity. The right-hander is 2-0 with a 2.25 ERA in two career starts and one relief appearance against the Astros. In a start June 7, he allowed two runs and struck out 11 over six innings of a 14-2 victory.Houston (48-100) didn't put up much more of a fight Tuesday, going 1 for 11 with runners in scoring position.The Astros need nine wins in their final 14 games to avoid surpassing last season's franchise-record 106 losses. They're enjoying the role of spoiler, having won three of four against Philadelphia over the weekend and eight of 16 overall this month."We know what's on their mind over there, to get that second wild-card spot," center fielder Justin Maxwell said. "If we can do our job and win games, we can definitely be the spoilers."Lucas Harrell (10-9, 3.86) will try to snap a five-start winless streak when he goes to the mound Wednesday.He allowed four runs and five walks over 5 2/3 innings of a 6-4 win over the Phillies on Thursday.The right-hander is 2-1 despite a 6.61 ERA in three starts against the Cardinals this year, most recently allowing six runs and eight hits over five innings of a 7-0 road loss Aug. 21.