PITTSBURGH -- Two bunts, one double and nine well-pitched innings. The Chicago Cubs proved on a Wrigley Field-like day they can win when their bats aren't booming, and their by-the-textbook victory came before they begin what may be their toughest stretch all season.

Jason Marquis shut down Pittsburgh's batters on a cool, windy day that must have made the Cubs feel at home, and Chicago turned two well-placed bunts into two runs in the seventh inning to sweep yet another three-game series from the Pirates with a 2-0 victory Wednesday.

"That's the sign of a good team, one that can win in different ways," Reed Johnson said. "We've been able to win the last couple of weeks by sitting back and swinging the bat. Today we weren't swinging the bats very well, so we were able to play a little bit different game and it ended up working out for us."

After scoring 26 runs -- 12 on Monday, 14 on Tuesday -- in the first two games, the Cubs turned to pitching and defense for their third three-game sweep this season of the NL Central rival Pirates. The Cubs won the season series 14-4, the most victories they've have against Pittsburgh since going 15-7 in 1954 -- and their most against any opponent since beating St. Louis 15 times in 1978.

Chicago, a major league-best 83-50, won its fifth in a row and 13th in 16 games. The Cubs are 33 games over .500 for the first time since they were 98-56 at the end of the 1945 season.

The Cubs went 7-2 in a nine-game stretch against NL weaklings Cincinnati, Washington and Pittsburgh. It gets tougher starting Thursday night against the Phillies as they play 27 of their final 29 against teams that are .500 or above.

"You've got to make sure to take same approach every pitch, every at-bat, every game and not let the mental errors and mental mistakes get to you," Marquis said. "That says a lot for this team, how good we feel we're going and how good we can be -- and how we're not going to let up until the season is over."

As if their schedule would let them do that.

The Pirates lost their season-high seventh in a row and 11th in 13 games despite one of Zach Duke's few effective starts since the All-Star break. Pittsburgh is 7-18 since trading leading run producer Jason Bay to Boston on July 31.

Asked if the Pirates are glad they won't see the Cubs until next season, manager John Russell needed only a one-word answer: "Yeah."

Duke (4-13), who lost his ninth consecutive decision, took a shutout into the seventh before Johnson beat out a bunt single to third. Mark DeRosa, batting .441 (15-for-34) during a nine-game hitting streak, doubled down the left-field line to put runners on second and third.

After Johnson scored on Ronny Cedeno's softly hit grounder to third, backup catcher Henry Blanco put down a perfectly placed squeeze bunt that stayed fair along the first-base line by inches to score DeRosa standing up.

"I thought it was going to go out (foul)," Blanco said. "It stayed in and everything was good and I got an RBI. Once again, we've got to do the little things."

Blanco started a night after starting catcher Geovany Soto drove in seven runs in a 14-9 Cubs victory keyed by a seven-run eighth inning.

"One ball left the infield and they got two runs, so what can you do?" Duke said.

Those were all the runs Marquis (9-7) needed in his best start since he pitched seven shutout innings against the Giants on July 11. A winner only twice in nine starts since June 26, Marquis limited the Pirates to five hits and walked none in seven innings while twice stranding runners at third.

"I felt like I did pretty well, especially against that offense, but Marquis was on his game so there's not a lot I could do," Duke said.

Winless in 14 starts since beating Arizona 5-3 on June 9, Duke gave up seven hits in eight innings -- the longest of his 27 starts. The left-hander went 0-3 against the Cubs in five starts.

Carlos Marmol pitched a scoreless eighth inning and Kerry Wood finished for his 27th save in 32 attempts. The three Cubs pitchers combined for a five-hitter and Chicago's seventh shutout of the season. Chicago did not allow a hit following Raul Chavez's leadoff single in the fifth.

Notes

• The Cubs have won 13 of their last 14 road games.
• All four of Duke's victories are at home, but he has lost his last six decisions there. Duke is winless in his last nine starts against the Cubs.
• The Pirates (57-76), fast approaching the 82nd loss that would ensure a major league record-tying 16th consecutive losing season, have fallen behind last season's pace, when they were 68-94. They were 59-74 at this point last year.
• The Cubs also swept the Pirates April 7-10 in Pittsburgh, a series that included a day off, and April 18-20 in Wrigley Field.
• The Pirates were shut out for the fifth time.