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After another late rally fell short, Geoff Blum admitted that something is missing in the Arizona Diamondbacks' clubhouse.

"Last year we'd find a way to scratch back in the ninth inning and squeeze out a win to keep that thing going, but this year a little bit of that magic is lost," Blum said. "Trying to get that momentum has been a little bit tougher this year."

Ryan Dempster tied the Cubs' record with a 33-inning scoreless streak, pitching six solid frames and leading Chicago over the Diamondbacks 4-1 on Saturday.

The Diamondbacks have dropped two in a row coming out of the All-Star break and have mustered up just two runs.

Cubs closer Carlos Marmol pitched a scoreless ninth for his ninth save in 11 chances. Marmol allowed a leadoff double to Stephen Drew and walked Chris Young. Blum followed with a deep fly ball to right, but Reed Johnson made a nice running catch up against the ivy, then Marmol got pinch hitter Jason Kubel to hit into a double play to end the game.

The Diamondbacks won 94 games and took the NL West by eight games in 2011, but Saturday's loss dropped them to three games under .500. They are still well within striking distance

"I don't think anybody is freaking out, but we'd like to get on a run and feel good about ourselves," Blum said. "We can make all kinds of excuses, but it's still on us to be professionals and go out there and get ready for a ballgame."

Arizona joined the growing list of teams that haven't been able to do anything against Dempster. He hasn't allowed a run since May 30.

The scoreless streak "is not a fluke," Diamondbacks manager Kirk Gibson said. "He located all of his pitches. He's a veteran guy. He got us sometimes where we were more aggressive and he got the best of us."

Dempster (5-3) allowed four hits and set a career best by winning his fifth straight start. He leads the majors with a 1.86 ERA.

Cubs manager Dale Sveum limited Dempster to 89 pitches. The right-hander made his second start since coming off the disabled list with tightness in his pitching shoulder.

"I was able to keep the ball down, keep it out of the air. They have a lot of guys who can hit it out of the ballpark," Dempster said.

Dempster struck out five and walked three. With the Cubs far back in the playoff race and Dempster in the last season of a four-year contract, he has become a possible trade option for contending teams.

Darwin Barney hit an RBI double for the Cubs, who have won 11 of their last 15 games.

Chris Young homered for Arizona in the seventh off James Russell. The Diamondbacks have lost eight of 11.

Joe Saunders (4-6) returned after being on the disabled list with a left shoulder strain and pitched six innings. He allowed three earned runs and eight hits.

"It was fun to get back out, start contributing again," Saunders said. "We knew runs were going to be hard to come by against Mr. Dempster out there."

Luis Valbuena led off the Cubs third with a single and Dempster sacrificed. Johnson reached on a bunt single and Starlin Castro beat out a potential inning-ending double play as Valbuena scored.

In the fourth, Alfonso Soriano led off with a single and later scored on Barney's two-out double. Three pitches later, Valbuena singled up the middle for a 3-0 lead.

The Cubs scored in the sixth on an error and Barney's double-play ball.

NOTES: The Diamondbacks optioned LHP Patrick Corbin to Triple-A Reno to make room on the roster for Saunders. Gibson said Corbin will work as a starter at Reno. He started five games for Arizona this year but had been appearing out of the bullpen of late. ... Kubel (right hamstring tightness) was held out of the starting lineup. Gibson said Kubel was still sore. Kubel was removed in the seventh inning of Friday's 8-1 loss after slipping several times on the slick field.