Wolf (9-11) struck out five in the first two innings and gave up six hits -- all singles -- in his first complete game in four years. Dempster (15-6) allowed three runs in seven frames, including a two-run homer by Ty Wigginton.
With Carlos Zambrano's unknown status and Rich Harden's unavailability, Piniella turned to the club's top healthy pitcher to break the skid. Dempster, who started the year 10-0 at home, fell to 12-3 at the suddenly Unfriendly Confines. Now, the club departs for a nine-game road trip as cold as it's been all season.
"You're going to have adversity along the way," Piniella said. "We're having it right now. We'll see how we respond."
Dempster has a remedy in mind.
"We've just got to come to the field and have a good day off [Thursday]," he said, "maybe go get some Einstein's Bagels in the morning, go for a nice run, then have a nice plane flight, go have a nice dinner and go to Cincinnati refreshed and put this behind us and just play well."
Even though the wind was steadily blowing in, Wolf struck out eight and walked two in his best start of the season. His last complete game came against the Montreal Expos on April 24, 2004, when he pitched for the Phillies.
"There were some balls hit hard, but you can't take anything away from Randy," said shortstop Ryan Theriot, who went 0-for-4. "I thought he threw the ball really well. It seemed like he was ahead of everybody throughout the game."
Wolf got help from two red-hot Houston hitters, Hunter Pence and Wigginton. Pence went 2-for-4 and finished the series 8-for-13 with three doubles and a triple. Wigginton's home run came on the heels of a 12-homer August.
Pence stretched a two-out double and scored on an Humberto Quintero single to put Houston up, 1-0, in the second. Eight of Houston's first nine baserunners reached with two outs, including Wigginton's liner through the wind and into the left-field seats in the fifth.
Dempster was befuddled.
"That was the most disappointing thing -- today I felt as good as I've felt all year," he said. "Warming up, I felt great, and mentally, I felt good. I just didn't execute a couple pitches, and they made me pay for it. You tip your cap to them."
Dempster battled to give the bats a chance and even pitched in at the plate with a pair of two-strike sacrifice bunts, giving him a Major League-leading 18 sacrifices for the season. It extended his franchise record, but Dempster wasn't patting himself on the back.
"No, not good enough," he said. "You don't have a 'good job' column in the paper tomorrow. It's not one of those, unfortunately. It'd be fun to have one of those."
The Cubs' best scoring chance was erased on a play at the plate in the fifth. Ronny Cedeno came around from second when Alfonso Soriano lined a single to left. Wigginton fired a one-hopper to Quintero, whose tag grazed Cedeno's back before the Chicago second baseman could slide past him.
The Astros scored their final run on a botched rundown with runners on first and third in the ninth. Reliever Jeff Samardzija appeared to catch Michael Bourn napping at first, but Bourn stayed alive while David Newhan stole home before Theriot's throw bounced to the catcher.
There's some positive news, however. The Brewers also lost, keeping the Cubs 4 1/2 games ahead in the division, and Chicago next plays Cincinnati, another team that hasn't won this month.
"I have a pretty good feeling that we're not going to lose every game in September," Dempster said. "So I think we'll be all right."