Pittsburgh right-hander Ross Ohlendorf will look to regroup in his second start after a lengthy stint on the disabled list with a right shoulder strain.
With Paul Maholm's left shoulder strain sending him to the DL, Ohlendorf was able to rejoin the rotation Tuesday for the first time in more than four months, but he allowed seven second-inning runs -- four earned -- on 11 hits for the loss.
Ohlendorf will be arbitration-eligible again this offseason, and other starters have taken steps forward while he was hurt. In order to put himself in a position to be a part of the rotation next season, Ohlendorf must finish strong.
"I'm really excited to be back," Ohlendorf said. "I definitely didn't think it would take as long as it did. I'm really glad that there is still some season to go."
Houston, meanwhile, will find its most consistent starting pitcher toeing the rubber.
Wandy Rodriguez is 8-6 with a 2.93 ERA in his last 19 starts since April 30. Over 123 innings, he has allowed 40 runs.
The southpaw is one of only seven pitchers in franchise history to record nine or more wins in at least seven seasons.
Since June 24, 2010, Rodriguez has the eighth-lowest ERA among all big league starters (2.81), and the third lowest among lefty starters.
"They're going to battle," manager Brad Mills said of his Astros, who are the only team in the Majors that has been officially eliminated from postseason contention. "You can call it grit, but these guys night after night just battle. The last four of five series we've played well and put ourselves in position to win a game, whether it's our pitching or hitting with runners in scoring position. That's what we want right now."
Pirates: One win shy of exceeding last season's division mark
Heading into the three-game series against Houston, Pittsburgh has the same number of wins this year (31) as it did against the National League Central all of last season.
Seventeen of the 31 victories have come on the road. Last year, the Pirates went 31-48 against their division, including 10-30 away from PNC Park.
The Pirates have 18 games remaining against the NL Central, nine of which are on the road.
Josh Harrison has gone 11-for-27 (.407) with three doubles, one triple, one home run, six RBIs and five runs in his last eight games.
Chris Leroux has been scored upon just once in his first nine appearances with the Pirates.
Astros: Relievers getting it done
Over Houston's past nine games, eight of them have been decided by two runs or fewer, including its 4-3, series-clinching victory on Sunday in extra innings against the Giants.
Though the club is 3-6 during that span, the bullpen has done its part.
Astros relievers have allowed 13 runs over the last 41 innings, which spans the past 13 games.
During the past four games, they have given up just two earned runs in 12 1/3 innings.
Brian Bogusevic is batting 18-for-49 (.367) with four homers and 12 RBIs in his last 19 games.
David Carpenter has not allowed a run in 19 of his 23 Major League appearances. He collected his first big league save on Sunday.
This will be the third and final trip the Pirates make to Houston this season. The club is 5-1 at Minute Maid Park.
Rodriguez is 1-1 with a 5.30 ERA over three starts against the Pirates this season. In July, he struck out 11 batters in 5 2/3 innings.