HOUSTON (AP) -- The Chicago Cubs left Houston banged up but in better shape.
Nomar Garciaparra homered one inning before leaving the game with a stiff lower back, but the shortstop and the formerly fading Cubs were feeling better after beating the Astros 4-2 on Wednesday night.
Garciaparra said his injury was not serious, and the Cubs won their second straight behind 8 1/3 innings from Carlos Zambrano to win the series after arriving in Houston having lost six straight on the road.
Garciaparra said he felt his back tighten up after lunging to catch Orlando Palmeiro's hard line drive in the second inning. He said he felt OK when he hit his solo homer two innings later but decided to leave in the fifth after having trouble moving around in the field.
"I'm not really concerned about it," Garciaparra said. "I know it's muscle and nothing other than that. I know it's matter of calming down. It's a good thing we have the day off tomorrow. I think with that day off and rest I'll be ready to go."
Zambrano (10-5) wasn't feeling entirely well, either, but the hard-throwing righty hardly showed it. Despite battling flu-like symptoms, Zambrano allowed two runs and three hits and struck out 10 for his third win in four starts. He homered leading off the third, his first of the season.
Zambrano is 6-1 in his last 10 outings.
"When a guy is throwing 97 mph and has a changeup about 84, you're not going to have a lot of good at-bats," Astros manager Phil Garner said.
The Cubs have won five of seven to get back in the NL wild-card chase after losing eight straight. Chicago trails the Astros by 5½ games.
"Every game is sort of crucial for us at this point," catcher Michael Barrett said. "It's do or die."
Roy Oswalt (14-10) gave up four runs and eight hits in seven innings. After a stretch of going 9-2, Oswalt is 0-2 with a 4.67 ERA in his last four starts.
"It just hasn't been going my way the last two or three starts," Oswalt said.
The Astros have dropped four of their last five, scoring a total of three runs in the losses. Houston got plenty of run support for Wandy Rodriguez in its 12-4 win Monday but has gotten a total of three runs for its three aces -- Oswalt, Andy Pettitte and Roger Clemens.
"There's no secret this team goes the way of our pitching," outfielder Lance Berkman said. "Our guys just have to hold them to two runs or less, and it's not fair to ask that of them."
Aramis Ramirez had a sacrifice fly for Chicago in the first. Zambrano homered in third, his first of the year, and Garciaparra made it 3-0 with his solo shot.
Garciaparra has played in 26 games this season, batting .242 with two homers and seven RBI. He was making his 10th start since returning after tearing his left groin in April.
In the bottom of the fourth, Garciaparra had to stretch to take a feed from first baseman Derrek Lee on a potential double-play grounder. Garciaparra got the force, but his relay was wide of first base and it rolled into the camera well. Garciaparra, who finished the inning, was charged with a two-base error as the Astros scored two runs on the play to cut the lead to 3-2.
The Cubs added another run in the seventh on Barrett's sacrifice fly.
The loss continued a disappointing homestand for Houston, which is 4-5 in its 13-game stay at Minute Maid Park. When the Astros came off the road on Aug. 7, they returned with the best home record in the majors.
Atlanta and Boston are now the top home teams in baseball with Houston's 40-20 mark ranking third.
After allowing two home runs in six starts during July, Oswalt has given up seven in his three August starts. ... The Cubs have homered in nine straight games, one shy of their season-best
mark. ... Two of Zambrano's four career homers have come at Minute Maid Park. ... Craig Biggio of the Astros is three doubles shy of 600 for his career.