CHICAGO (AP) -- Houston's latest victory was a tough one for manager Phil Garner to sit through.
The Astros earned their first three-game sweep at Wrigley Field since May 15-17, 2001. They have won four straight overall and eight of 11.
"A little frightening, but we got it done," Garner said.
Chris Burke and Lance Berkman began the eighth with consecutive singles off Bob Howry (2-2). One out later, Preston Wilson hit a sharp grounder to Todd Walker, who is playing first in the absence of Derrek Lee, and his off-balance throwing error to second loaded the bases.
Ausmus then grounded a single to right field, giving Houston the lead. Berkman scored the winning run ahead of a poor throw from Jacque Jones.
Ausmus was glad to redeem himself after hitting into a double play with the bases loaded in the Astros' 9-2 win over the Cubs on Tuesday.
"It was nice to come up with the bases loaded and do something positive," he said.
Michael Barrett hit a single to lead off the bottom half for the Cubs, but Walker quickly grounded into the easy double play.
"It seems like the majority of this year we've found ways to lose and you can pin today directly on me," Walker said.
Walker wasn't the only Cub struggling to hit with runners on. Chicago stranded two runners at third with less than two outs, most notably in the seventh when Freddie Bynum hit a leadoff triple. Juan Pierre stole second base four times but scored only once.
"This was a tough one to take," Cubs manager Dusty Baker said. "You just get tired of the same kind of thing. The guys are busting their [humps] but just coming up short."
Carlos Zambrano held Houston in check for seven innings. He gave up five hits, struck out five and walked two. He said he got tired early and that was why Baker lifted him after 107 pitches.
"He was out of gas," Baker said. "He threw a lot of pitches in the middle innings. He gave it all he had. We certainly didn't want him to throw 120, 125 pitches again."
The Astros certainly weren't complaining.
"We were just getting ready to hit," Garner said jokingly of Zambrano's exit. "I was glad, obviously."
Zambrano has thrown at least 101 pitches in all of his 15 starts. He threw 126 in each of his two previous outings, but the Venezuelan right-hander has always been comfortable with a heavy workload. He has thrown more than 200 innings in his three full seasons.
"My arm was heavy," Zambrano said of leaving after seven innings. "At some point of the season, this always happens to me."
Pierre stole a career-best four bases and Jones homered for the Cubs, who have lost 15 of their last 21 home games.
"You just hope that doesn't come back to haunt you and today it did," Pierre said.
Jones hit a solo homer off Fernando Nieve leading off the second, giving the Cubs a 2-0 lead.
Pierre's only run came in the first when he scored on Barrett's sacrifice fly. Pierre reached on a bunt single, stole second on a pitchout and went to third on Womack's sacrifice. Pierre finished 2-for-3.
Nieve gave up two runs and six hits in 5 2/3 innings.
Pierre had stolen three bases six times. ... Baker stacked his lineup with five left-handers, not including the switch-hitting Zambrano, against Nieve, who had struggled against left-handers this season. ... Baker celebrated his 57th birthday. ... Baker said right-hander Mark Prior will throw a side session Friday in anticipation of a possible start Sunday. ... The Cubs are 0-6 on Thursday. ... Burke is hitting .400 (14-for-35) over his last nine games. ... The Cubs have been swept six times this season.