By NOEY KUPCHAN
(AP) -- The St. Louis Cardinals' Adam Wainwright finally earned his first win in 20 months despite not having his best stuff.
He's piled up frequent victories against the Houston Astros over the course of his career.
Wainwright seeks to defeat Houston for a fourth straight time Sunday and help the NL Central-leading Cardinals avoid a three-game sweep at the hands of an Astros club riding its longest winning streak in almost two years.
Wainwright (1-3, 6.75 ERA), who missed all of 2011 after tearing the ulnar collateral ligament in his throwing elbow, lost his first three starts of the season while compiling a 9.88 ERA.
He's pitched better the last two times he's taken the mound. After striking out a season-high seven over six innings of one-run ball during a 3-2, 10-inning loss to the Chicago Cubs on April 24, Wainwright allowed four runs over a season-high seven innings in Tuesday's 10-7 victory over Pittsburgh.
"I think if you look at 90 percent of my game (Tuesday), it was pretty good," Wainwright said. "I feel like each time I'm getting a little sharper.
"I'm more concerned with the quality of my pitches and execution throughout the game, and I feel like I'm on the right track."
The Astros (13-14) know all too well of how formidable Wainwright can be. The 2010 NL Cy Young runner-up has defeated Houston more than any other opponent, going 9-1 with a 1.56 ERA in this series.
Wainwright has thrown eight scoreless innings in each of his last three meetings with the Astros, going 3-0 while limiting them to a .185 average. He's made things especially difficult on veteran slugger Carlos Lee, limiting him to one hit in 26 career at-bats.
However, Wainwright now must face a surging Astros team. Houston, which has outscored opponents 31-13 during its five-game winning streak, hasn't won six in a row since a seven-game run July 27-Aug. 3, 2010.
One night after defeating the Cardinals 5-4 in the series opener, the Astros prevailed 8-2 on Saturday. Third baseman Chris Johnson went 2 for 4 with his first career grand slam while Bud Norris allowed one unearned run over six innings.
Following Norris in the rotation is J.A. Happ (2-1, 4.60), coming off his fourth quality start in five outings this season. He yielded three runs while scattering six hits and three walks over 6 1-3 innings of Tuesday's 6-3 victory over the New York Mets.
"Compared to last year, it's a good stretch," Happ, who went 6-15 in 2011, told the Astros' official website. "I feel good, and I felt probably better than the results maybe even tonight. I'm just trying to keep going with that as long as I can."
The left-hander is 1-6 with a 6.44 lifetime ERA against the Cardinals - his highest ERA against any team he's faced more than twice. He lost all four of his starts against St. Louis last season.
Astros outfielder Jordan Schafer, who did not play Saturday, could get a chance to extend his streak of reaching base safely in 25 straight games - tied with Denis Menke for the longest in franchise history to open a season.
Houston is looking to get back to .500 for the first time since it was 4-4 on April 14.
Losers of a season-worst three in a row, the Cardinals (16-11) haven't dropped four straight since a seven-game slide June 10-17.
Former Astros slugger Lance Berkman (strained left calf) was eligible to come off the disabled list Friday for St. Louis but has yet to return. His status for this game is uncertain.
Updated May 5, 2012