CHICAGO -- With little punch in the lineup, the Padres can't afford to fall apart in other aspects of the game, but that's what happened Monday night in what was probably the ugliest loss in an already nasty start to the season.

The Cubs took advantage of bad pitching and subpar defense, batting around in consecutive innings as they routed the Padres, 12-3, in the opener of a four-game series.

The onus for this one can be placed on Randy Wolf, who allowed all seven Cubs hitters he faced to reach base in the six-run fifth, including Alfonso Soriano, who hit a two-run homer to start the carnage and end San Diego's brief two-game winning streak. These were the most runs the Padres have given up in a game this season, and conversely, they couldn't do much offensively against Cubs ace Carlos Zambrano.

"Every loss is disappointing," Padres manager Bud Black said. "But if you look at our daily log, we don't have games like that. We're in games. In this one, the middle part of the game got away from us."

Wolf (2-3) was charged with seven runs on eight hits and five walks and left with no outs in the fifth. He's given up 23 runs in his last five starts as his ERA has spiked from 2.49 to 5.16. He's lost two straight starts and his last three decisions. His pitches were up, and when that happens, hitters can tee off.

"I'm just not executing pitches when I need to, and things have kind of snowballed in a couple innings," Wolf said. "In the fifth inning, there's no way to candy-coat it, I was bad. I didn't make the pitches I needed to, and they capitalized on it."

Zambrano led off the fifth with a double and scored on Soriano's fourth homer of the year, a blast to left-center. Wolf walked Ryan Theriot and gave up singles to Derrek Lee and Aramis Ramirez to score another run. He then walked Kosuke Fukudome and gave up a two-run single to Geovany Soto. That was all for Wolf.

"I think Wolfy has pitched well this season," Black said. "And when he has gotten into jams, he's been able to get himself out of them. Tonight wasn't the case."

Sean Henn came in and promptly gave up a run-scoring single to Mark DeRosa before Reed Johnson hit into a double play and Zambrano struck out to end the inning.

The Cubs scored five more in the sixth. Henn walked Fukudome with the bases loaded, and the Cubs scored three more on a strange play. With two outs, DeRosa hit a grounder to deep third, but Ramirez beat Kevin Kouzmanoff to the bag as a run scored. Kouzmanoff then uncorked what looked like a wild throw to first as Adrian Gonzalez, thinking the out was made and the inning over, was already walking off the field. Tack on two more runs to make it 12-2.

"That was a bonehead play by me," Gonzalez said, though the error was charged to Kouzmanoff. "I assumed the out was made and started getting off the field. The ball was thrown in right field, and it was my fault."

Gonzalez's play unwittingly allowed his brother to make his Major League debut. Edgar Gonzalez, just added to the 40-man roster Monday, came in for Kouzmanoff at third and got his first hit in the seventh, a single up the middle off Zambrano that scored Scott Hairston.

"It was a bad situation we were in as a team, but I got my feet wet and was able to get my first at-bat and get the butterflies out of the way," Gonzalez said. "I was happy to get in there."

Jody Gerut had two hits from the leadoff spot and gave the Padres a brief 2-1 lead in the top of the fifth, when he hit his first home run since May 1, 2005, a solo shot to Sheffield Ave. in right. Tadahito Iguchi had an RBI single in the third. Hairston also had two hits.