Rodriguez (5-3) did not walk a batter, struck out seven and threw 71 of his 103 pitches for strikes.

Four Houston players drove in one run, including shortstop Miguel Tejada, who had two of the six hits in the Astros' fourth straight victory.

Closer Jose Valverde fanned two of the three batters he faced in the top of the ninth to record his 25th save this season.

Losing pitcher Carlos Zambrano ended Rodriguez's shutout bid with a solo homer in the top of the seventh. Ryan Theriot had three of the nine hits for the Cubs, who have dropped three in a row.

Zambrano (10-4) surrendered four earned runs and six hits in 6 1/3 innings with six walks and three strikeouts.