The NL Central race will go down to the final day of the season.
Houston, which has lost nine of 13, held onto a share of first because the Reds lost 4-3 in 10 innings as Milwaukee. In the wild-card race, the Reds and Astros (95-65) saw their lead over the New York Mets (94-66) cut to one game with two games to play.
The Astros had plenty of scoring chances against the Dodgers but they couldn't take advantage of any of them against Eric Gagne (1-1), who got his first major league victory.
"I knew this would be a tough series with three teams fighting for two playoff spots," Jeff Bagwell said. "We didn't play very well. We deserved to lose. All you can do is the best you can."
Gagne allowed five hits in six innings as Los Angeles won for the 10th time in 13 games.
"We've battled through things all year and had a lot of injuries," Houston's Craig Biggio said. "It's a dog fight with two games to go, so we'll see how it goes."
Gagne walked five and struck out five, including Ken Caminiti with runners on in the first and third innings.
"Gagne was outstanding. He didn't have real good command like he usually does and he threw a lot of balls," Dodgers manager DaveJohnson said. "But he made the pitches when he had to and he got his first major league win."
Eusebio's RBI double in the eighth off Alan Mills gave Houston its run.
Shane Reynolds (16-14), who has two wins in 11 starts since Aug. 5, allowed five runs and eight hits in five innings.
"We've got a couple of games left and anything can happen," Reynolds said. "There's no sense to worry about this. We've just got to do our job here. We can't worry about what's happening elsewhere."
Sheffield hit a two-run single in the third and Adrian Beltre had an RBI single.
Sheffield is trying to become only the second player Dodger to hit .300 with 30 homer, 100 RBIs, 100 runs and 100 walks. Duke Snider did it in 1955.
"We're not paying attention to which teams are in it," Sheffield said. "We know Houston is one of the team and if we are the spoilers the that's the way it is."
"We're just trying to play hard and find out if some of our young guys can play. We don't care who's in it and who's not, who we help and who we don't help. Whoever it is, they've got to earn it."
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