Red-hot Carlos Zambrano pitched seven scoreless innings and Blake DeWitt drove in the only run as the Chicago Cubs dealt the San Diego Padres a critical 1-0 defeat on Monday night at Petco Field.

The loss dropped the Padres (87-69) one game behind the San Francisco Giants (88-68) in the National League West with six games to play and one-half game back of the Atlanta Braves (88-69) in the wild card race.

Zambrano (10-6) scattered three hits and four walks and struck out five to improve to 7-0 with a 1.27 ERA in 10 starts since returning from his suspension for unprofessional conduct. The right-hander has surrendered fewer than three runs in all 10 starts and his winning streak is tied for the second longest of his career.

Sean Marshall worked a perfect eighth with two strikeouts and Carlos Marmol closed the door on the Cubs' 12th shutout in the ninth when he retired Nick Hundley with the bases loaded for his 35th save.

Zambrano and San Diego starter Tim Stauffer exchanged zeros until the Cubs broke through in the seventh on a double by Alfonso Soriano and a run-scoring single by DeWitt.

DeWitt finished with three hits for Chicago, which beat San Diego for the first time this season. The Padres swept a four-game set at Wrigley in mid August.

Stauffer (5-5) allowed just the one run and five hits in seven frames with two walks and five strikeouts.