HOUSTON -- When he signed a six-year, $85 million contract during Spring Training in 2005, first baseman Lance Berkman said he wanted to remain with the Astros for the rest of his career. Berkman hasn't swayed from those beliefs, but he's not sure if he will play beyond the length of the contract.

Next season is the last year of the deal, but the Astros have an option for 2011 worth $15 million, which they almost certainly will pick up. If they don't, Berkman becomes a free agent after next year and the Astros will pay him a $2 million buyout.

"I'm going to play next year because I'm under contract, and if they pick up the option, we'll see where I'm at after that year," he said. "That's kind of how I'm viewing it."

Berkman, 33, is hitting .272 with 18 home runs and 65 RBIs, which is well below his career numbers. He missed 18 games in late July and early August because of a strained left calf and hasn't hit a home run since July 9, a span of 92 at-bats.

Berkman, who ranks first in team history in batting average and slugging percentage, second in homers and third in RBIs, doubles, runs and total bases, said he won't continue to play if he's not performing at a high level.

"I don't think that's fair to the team or to me," he said. "If I'm not going to perform a level I'm comfortable with, I'm not going to play. I'm going to play next year because I'm obligated to play. I'm going to give as a good of an effort as I can, and see what happens. If I have a good year and they pick the option up, I'll be committed for another year.

"I don't want to hang around. I don't want to hamstring the organization, and I don't want to take away from my family and things like that. If I'm not as productive as I want to be, I'll take it to the house."

Pitching matchup
HOU: RHP Roy Oswalt (8-5, 3.80 ERA)
Oswalt won for the second time in three starts on Monday by holding the Cubs to six hits and two runs in seven innings at Wrigley Field. He went 2-1 in August, improving his career record for the month to 28-7. But he's been equally as dominant in his career in September and October, going 28-8 with a 2.54 ERA in 44 starts. Last year, he was 5-1 with a 1.42 ERA in six September starts. Oswalt is 6-1 with a 3.28 ERA in 10 career games (eight starts) against the Phillies. He was 1-0 against Philadelphia last year in one start.

PHI: RHP Joe Blanton (9-6, 3.77 ERA)
Blanton was outstanding in his previous outing, against the Braves on Sunday. The hard-throwing right-hander gave up three hits and one earned run in seven strong innings, his career-best 10th straight quality start. Blanton was around the plate most of the night and threw 111 pitches, including 66 for strikes. The only run he surrendered was a solo homer to Martin Prado in the first inning. Blanton settled down after that and shut down Atlanta the rest of the way.

Tidbits
Houston center fielder Michael Bourn leads the National League with 49 steals and is one shy of becoming the first Astros player since Craig Biggio (1998) to reach 50. ... Miguel Tejada entered Friday leading all NL shortstops in games (130), total chances (585), assists (392) and double plays (89). ... Entering Friday, Houston's .645 winning percentage (20-11) against Philadelphia since the start of the 2004 season was the highest of any NL club.

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Up next
• Sunday: Astros (Bud Norris, 3-3, 6.61) vs. Phillies (Cole Hamels, 8-8, 4.26), 1:05 p.m. CT
• Monday: Astros (TBD) vs. Phillies (TBD), 1:05 p.m. CT
• Tuesday: Astros (TBD) vs. Braves (Javier Vazquez, 11-9, 3.18), 7:05 p.m. CT