Houston starting pitcher Randy Wolf celebrates with teammates after he threw a six-hitter in the Astros’ 4-0 win over the Chicago Cubs on Wednesday in Chicago. Nam Y. Huh / The Associated Press

CHICAGO — Randy Wolf’s first shutout in more than four years gave the Houston Astros another lift in their impressive late-season surge.

Wolf pitched a six-hitter Wednesday night and the Astros ran their latest winning streak to eight games with a 4-0 victory over the slumping Chicago Cubs, who have lost a season-high five in a row.

“It’s really gratifying the fact that I’ve been through a lot the last three or four years — two surgeries — and it’s been a long way back,” said Wolf, who’s had procedures on both his elbow and shoulder since 2005.

“It makes it sweet to do it against such a good team and in Wrigley. It was exciting. I know it’s been a long time. So it’s nice.”

Wolf (9-11) walked two and struck out eight, including Reed Johnson to end the fourth when the Cubs had two on. It was the 31-year-old left-hander’s eighth career shutout and first since April 24, 2004, when he beat the Montreal Expos 7-0 while pitching for the Phillies.

Wolf needed 128 pitches to go the distance but was able to give the Astros’ bullpen some rest.

“(Closer Jose) Valverde got on his knees before the game and did the sign of the cross four times begging for me to go nine,” Wolf said.

Wolf got plenty of support Thursday night from Ty Wigginton, who continued his homer tear with his 22nd of the season and also made a great throw from left field to cut down the run. The win gave Houston its second eight-game winning streak in less than a month, matching an earlier one from Aug. 7-14. And now the Astros have suddenly re-emerged in the NL wild card picture.

“It gives us something to play for in September,” Wolf said. “I know that we still have a ton of ground and some miracles for this to happen, but it’s one of the reasons you don’t give up.”

In other games on Wednesday: NATIONAL LEAGUE

Diamondbacks 4

Cardinals 3

PHOENIX — Adam Dunn doubled home the winning run in the ninth inning, and Arizona beat St. Louis.

Mets 9

Brewers 2

MILWAUKEE — Ryan Church hit a grand slam and Brian Schneider added a homer in New York’s six-run first inning and the Mets completed the three-game sweep.

Giants 9

Rockies 2

DENVER — Barry Zito won for the third time in four starts and Nate Schierholtz had a career-high four hits for San Francisco. Colorado had won seven of 10, including the first two games of the three-game series.

Marlins 5

Braves 3

MIAMI — Hanley Ramirez homered and doubled to lead Florida in front of an incredibly sparse crowd. Fewer than 600 people were in Dolphin Stadium for the first pitch.

Nationals 9

Phillies 7

WASHINGTON — Cristian Guzman set a Washington franchise season record with his eighth consecutive multihit game, capping it with a bases-clearing double in the decisive eighth inning.

Pirates 6

Reds 5

CINCINNATI — Adam LaRoche snapped an zero for 16 slump with two RBI singles to lead Pittsburgh.

Dodgers 6

Padres 4

LOS ANGELES — Blake DeWitt and Angel Berroa hit back-to-back homers in the fourth inning to put Los Angeles ahead for good, and the Dodgers completed a sweep of the three-game series. AMERICAN LEAGUE

Red Sox 5

Orioles 4

BOSTON — Dustin Pedroia homered in the seventh inning to begin Boston’s comeback from a four-run deficit, and the Red Sox beat Baltimore when pitcher Jim Miller’s threw away a bunt for a game-ending error.

White Sox 4

Indians 2

CLEVELAND — Nick Swisher and Alexi Ramirez homered to help Chicago avert a three-game sweep. Javier Vazquez (11-12) allowed two runs in six innings and Bobby Jenks recorded the final five outs for his 28th save.

Rangers 1

Mariners 0

ARLINGTON, Texas — Texas fill-in starter Dustin Nippert allowed seven hits in seven innings, and Milton Bradley hit a sacrifice fly in the first inning for the game’s only run.

Yankees 8

Rays 4

ST. PETERSBURG, Fla. — Alex Rodriguez’s ninth-inning homer was upheld in baseball’s first use of instant replay, and New York beat Tampa Bay.

Blue Jays 5

Twins 4

TORONTO — John McDonald singled home the go-ahead run in the 11th inning and Toronto beat Minnesota for the eighth straight time.

Tigers 9

Angels 6

DETROIT — Placido Polanco had three hits and drove in three runs, and Mike Hessman homered for Detroit, which won for the third time in 10 games. Athletics, Royals game wiped out by rain

KANSAS CITY, Mo. — Heavy rains forced the Kansas City Royals to postpone their game against the Oakland Athletics.