With his team trailing, 5-4, in the ninth, Corey Koskie singled off of Dempster. Damian Miller walked, and Gabe Gross then bunted. Dempster fielded the ball and threw past Aramis Ramirez at third base for an error, allowing Koskie to score the tying run.
Pinch-hitter Corey Hart hit the ball through the legs of shortstop Ronny Cedeno for another error, allowing the go-ahead run to score. Rickie Weeks and Geoff Jenkins each hit sacrifice flies to make it 8-5.
"I've never in my entire career thrown that ball away," Dempster said. "I make that play every day in Spring Training and every day before the game. You've got to be better than that."
What hurts the most is that the Cubs had rallied twice, including scoring two runs in the eighth. Carlos Zambrano did everything -- hitting a two-run homer and pitching eight innings. But the Cubs now are at a season-worst 20 games under .500.
"It really breaks my heart because Z pitched his tail off," Dempster said of Zambrano. "He came up with a big hit and got it going, got energy going, the guys came back, we fought, we scrapped, the fans were behind us 100 percent as loud as it got. It [stinks], it really [stinks].
"It's embarrassing to me," Dempster said. "I know how to get guys out, I know how to pitch guys, I know how to get ahead, I know how to field my position, and I didn't do many of those things today. It's really disturbing to me. If this is rock bottom, I guess we hit it. That was a really, really tough game today."
The crowd of 39,399 let the Cubs know they weren't happy. Dempster understood.
"We're 20 games under .500 -- I'd be [ticked] off if I was a fan," he said. "I wish they could understand how bad I feel. It's not fun losing like this, it's not fun blowing a game like that especially when the team goes out there and every single person does their job and you don't do it. That's a tough pill to swallow."
It seems as if Dempster has gotten more work on the side than in a game, but this has been a tough month. He's given up 11 runs over 8 2/3 innings in eight games in June. Cubs manager Dusty Baker said he'll talk with pitching coach Larry Rothschild about their options.
"We got him an inning in Minnesota, so he could be sharp for these situations," Baker said of Dempster. "He hasn't been sharp for awhile. His command hasn't been where it usually is and his slider isn't as sharp. That was a tough one that got away tonight."
Zambrano tried. He hit a two-run homer, his second of the year, and gave up four runs on six hits, including Carlos Lee's homer leading off the top of the fourth. It was the 55th homer by an opponent at Wrigley Field. The Cubs, on the other hand, have hit just 26 homers at home, including Zambrano's line drive in the fifth.
"This is not the time to blame anybody or point at somebody," Zambrano said. "This is the time to stay together and support each other. We have to keep playing."
But why are the Cubs playing so poorly?
"I don't know," Zambrano said. "I think we're running into bad luck. Sometimes you have to have luck. We're missing that. I don't know what to say right now. We just have to keep playing good and playing together."
The Brewers have been there, done that.
"We've been in the same situation [as the Cubs]," Jeff Cirillo said. "We've been in losing streaks and bad things happen. We don't feel sorry for them, because we've been in the same situation."
The Brewers took a 1-0 lead in the third in a strange way. Gross was at second with one out and Weeks hit a grounder to Cedeno. Gross escaped a rundown between second and third, although Cedeno thought he tagged him and Baker thought he ran out of the basepath. Gross then scored on Bill Hall's groundout.
"That run was haunting us early," Baker said. "The two runs in the ninth made it tougher."
Just ask Dempster.
"As tough as it is, you've got to stay positive, you've got to stay happy," he said. "Tomorrow's a new day and today [stinks]. Today really [stinks]."