Geoff Blum singled in the winning run with the bases loaded in the bottom of the ninth to lift the Houston Astros to a 2-1 win over the Chicago Cubs on Wednesday night.

The Cubs wasted a dominant start from Carlos Zambrano, who allowed a run on three hits through eight innings.

Angel Guzman replaced Zambrano and Miguel Tejada led off the ninth with a single. Hunter Pence walked, and Carlos Lee flew out to center, with Tejada tagging to third with a head-first slide.

Guzman (2-1) intentionally walked Lance Berkman to load the bases and Blum lined a single up the middle, bringing home Tejada.

Chris Sampson (3-0) pitched two scoreless innings in relief of Wandy Rodriguez to earn the victory.

Geovany Soto hit a solo homer in the second inning for the Cubs, who dropped to 5-2 at Minute Maid Park this season.

Zambrano, who no-hit the Astros last Sept. 14, breezed through the Houston lineup again on Wednesday, allowing only two hits with a strikeout through six innings.

He retired 14 in a row before Michael Bourn walked with two outs in the sixth. Tejada, who came in with a .467 career average against Zambrano, then lined out to Aaron Miles at second base.

The Cubs got five hits through five innings off Rodriguez, but left five men on base.

Rodriguez struck out two Cubs in the sixth, then fanned Zambrano to end the seventh. The 30-year-old left-hander hadn't lasted seven innings since his last win, against Milwaukee on May 20.

Pence walked leading off the Houston seventh and went to third on Lee's single. Lee came in with a .347 lifetime average against Zambrano.

Pence scored on Blum's groundout to tie the game.

Sampson relieved Rodriguez for the eighth. Rodriguez threw 116 pitches, a season high. Sampson gave up two singles, but struck out pinch-hitter Kosuke Fukudome to end the inning.

Zambrano threw 104 pitches.

The Cubs dropped to 25-5 when leading after six innings and 20-8 when they score first this season.

NOTES: Houston manager Cecil Cooper rearranged his pitching rotation to give RHP Roy Oswalt extra time to recover from minor soreness in his right wrist. RHP Russ Ortiz (3-2) will start Thursday's series finale, replacing LHP Mike Hampton (4-4), who will now pitch Friday in Arizona. Oswalt (2-3) also moves back a day and will pitch against Arizona on Saturday. ... The Astros outrighted the contract of right-handed reliever Geoff Geary to Triple-A Round Rock. Geary has three days to accept the assignment or become a free agent. ... The Cubs activated Miles from the disabled list (shoulder strain) before the game and optioned Jake Fox to Triple-A Iowa.