Houston (55-45) at Milwaukee (40-59)

Roy Oswalt has won two of three starts since his latest return from a nagging groin injury. But he’s still uneasy about his health.

“The biggest thing is my velocity’s down right now, which kind of worries me,” Oswalt admitted.

The 25-year-old right-hander hopes for renewed life on his fastball as the surging Houston Astros meet the Milwaukee Brewers in the opener of a two-game set at Miller Park.

Oswalt has been battling groin problems for much of this season, originally suffering the injury May 15 while running the bases against Pittsburgh.

He was on the disabled list until May 31 but was sidelined again after straining the groin in the Astros’ 8-0 win over the New York Yankees on June 11—the game in which a record six Houston pitchers combined on a no-hitter.

Oswalt is 2-1 with a 3.96 ERA since his latest comeback, including Thursday’s 5-3 win over Cincinnati. He yielded three runs, all on solo homers, and six hits over 6 2-3 innings, striking out four and walking one.

But his fastball stayed well below the norm, causing concern for Oswalt and the Astros.

“I felt fine, I guess I’m just going through a little dead arm,” Oswalt said. “I’ve been in three starts in two months. I think that has something to do with it.”

Houston has won five of six since the All-Star break, capped with Thursday’s 2-0 win over Pittsburgh as rookie Jeriome Robertson tossed a three-hitter for his first career shutout.

Morgan Ensberg hit his 19th homer, and Robertson added an RBI single as the teams split the two-game series. The NL Central-leading Astros have also won 11 of 13.

The Brewers snapped a two-game skid with Tuesday’s 6-4 win over the Cincinnati Reds in a matchup of two of the NL’s lowliest teams.

Shortstop Bill Hall, playing just his second game this season, drove in two runs with a triple and a double in his first start for Milwaukee, which has lost seven of 10.

STANDINGS: Astros - 1st place, NL Central. Brewers - 6th place, 14 1/2 GB, NL Central.

ASTROS PROBABLE STARTER: Oswalt (6-5, 3.22 ERA). Oswalt has struck out 13 and walked just three over 18 2-3 innings since his returning from the DL. He is 4-3 with a 3.52 ERA in seven career starts against the Brewers.

BREWERS PROBABLE STARTER: Glendon Rusch (1-12, 7.99 ERA). Rusch tied a franchise record for futility with Thursday’s 7-2 loss to Pittsburgh—his 11th straight defeat. While tying Chris Bosio’s 1988 mark, the left-hander allowed five runs and eight hits over 4 2-3 innings, striking out four and walking one. Rusch is 2-5 with a 4.60 ERA in eight career starts against Houston.

OFFENSIVE LEADERS: Astros - Richard Hidalgo, .329 avg.; Jeff Bagwell, 21 HRs; Lance Berkman, 64 RBIs and 68 runs; Adam Everett, 6 SBs. Brewers - Scott Podsednik, .309 avg.; Richie Sexson, 26 HRs and 73 RBIs; Sexson and Geoff Jenkins, 62 runs; Posednik and Eric Young, 20 SBs.

SEASON SERIES: Brewers, 4-3.

STREAKS AND NOTES: Astros - RHP Oswalt is 19-9 with a 3.42 ERA in 41 career road appearances, including 35 starts. … OF Hidalgo is hitting .354 (52-for-147) with 14 doubles, 10 homers, 28 RBIs and 25 runs scored since being activated from the DL on June 7. … OF Craig Biggio has reached base in 27 consecutive games. Brewers - OF Jenkins is batting .500 with a double, a homer and three RBIs in 10 career at-bats against RHP Oswalt. … INF Wes Helms is batting .318 (14-for-44) over his last 11 games. … LHP Wayne Franklin went 1-for-2 with an RBI on Tuesday to continue a stretch of hot-hitting for Milwaukee’s pitchers. Brewers pitchers are hitting .333 (8-for-24) with two doubles and three RBIs over their last 11 games.

ROAD/HOME RECORDS: Astros - 23-27 on the road; Brewers - 19-34 at home.

INJURIES: Astros - INF Jose Vizcaino (wrist), 15-day DL; LHP Carlos Hernandez (shoulder), 15-day DL; RHP Rodrigo Rosario (shoulder), 15-day DL; RHP Brian Moehler (elbow), 60-day DL. Brewers - RHP Jayson Durocher (shoulder), 15-day DL; LHP Matt Ford (elbow), 15-day DL; RHP Nick Neugebauer (shoulder), 15-day DL; RHP Ruben Quevedo (shoulder), 15-day DL; RHP Todd Ritchie (shoulder), 15-day DL.