Chicago ? Carlos Zambrano’s back began to tighten up again. This time, he stayed around long enough to get the win.

Zambrano allowed six hits over six shutout innings Friday to lead the Chicago Cubs to their second straight victory over the St. Louis Cardinals, 4-1.

“The third inning it started to bother me. I went as far as I could,” Zambrano said.

Zambrano (9-5), who had to leave his previous start against the Mets after three innings because of a stiff back, was visited on the mound by Dusty Baker and a trainer after he retired Abraham Nunez on a fly ball in the sixth.

Albert Pujols followed with a double, and Zambrano walked Jim Edmonds before fanning John Rodriguez and getting Mark Grudzielanek on a fly to right-center to end the inning.

That was it for Zambrano, who didn’t return for the seventh against a team he has pitched well against all season. He’s allowed St. Louis just two earned runs in 232â3 innings over three starts. Teammates Neifi Perez and Aramis Ramirez told Baker that Zambrano was hurting.

“He said he could go one more. But you could see he was laboring out there, throwing the ball high,” Baker said.

“You hate to have a guy have back problems, then he starts changing his arm angle and compensating for it and you end up hurting something else. His teammates, they really convinced me he had had enough.”

Michael Barrett had two doubles and then homered in the eighth for the Cubs, who had lost eight straight before beating the NL leading Cardinals twice. Chicago still is 17 games behind St. Louis in the division.

“Baseball is like that,” Zambrano said.

“I don’t know how to explain it,” Barrett said. “There is a little extra adrenaline, and it’s fun to play in a rivalry like that.”

Roberto Novoa pitched the seventh, Kerry Wood gave up a single and walk in the eighth, and Ryan Dempster allowed an RBI single to Skip Schumaker in the ninth. Right fielder Jeromy Burnitz slipped on the play, allowing the ball to drop in and Einar Diaz to score from second.

Nunez grounded out to end the game with two on and Pujols in the on-deck circle.

Nationals 4, Rockies 2

Denver – Esteban Loaiza pitched into the seventh inning for his first victory in nearly a month, and Jose Guillen had a two-run single in the first inning, helping Washington defeat Colorado. Washington had just seven hits but got by on solid pitching to win for the fourth time in 16 road games and stay three games behind Houston in the NL wild-card race.

Phillies 3, Padres 2

San Diego – Pat Burrell hit a three-run homer, and Jon Lieber pitched six strong innings, leading Philadelphia. Burrell staked Lieber to a 3-0 lead in the first inning when he lined a 96 mph fastball off Jake Peavy into the left-field seats. Lieber and three relievers made it stand up.

Astros 6, Pirates 5

Houston – Morgan Ensberg hit a tying home run in the eighth inning, and Adam Everett scored three batters later on Rob Mackowiak’s throwing error, rallying Houston. Dan Wheeler (2-3) allowed one run on one hit in the eighth, and Brad Lidge pitched the ninth for his 29th save in 32 chances.

Diamondbacks 8, Braves 0

Atlanta – Tony Clark drove in four runs with his first two-homer game of the season, and Claudio Vargas allowed two hits in seven innings as Arizona beat Atlanta. Clark hit two-run homers in the first and third innings, giving him 21 – his best mark since hitting 31 for Detroit in 1999.

Vargas, claimed on waivers from Washington on June 3, walked two and struck out five. He retired 14 straight batters before Chipper Jones’ two-out single in the sixth inning.

Reds 5, Brewers 3

Milwaukee – Cincinnati’s Luke Hudson pitched six solid innings to remain unbeaten against Milwaukee. Hudson (4-5) improved to 3-0 in four career starts against the Brewers by giving up three runs and five hits – including two homers by Rickie Weeks. He walked five and struck out three.

Giants 1, Marlins 0

Miami – Noah Lowry pitched 71â3 innings, and Randy Winn homered in the sixth to help San Francisco. The Giants won with only five hits off Dontrelle Willis (15-8).