The pitching hero was Jason Marquis, who picked up his first victory since June 21 against the White Sox.
Marquis survived 61/3 innings and DeRosa hit a grand slam that put his team ahead for good in a rousing 11-4 triumph over Houston. It marked the Cubs' 33rd comeback victory of the season and gave them a 4-0-1 record in their last five series.
With their first off-day in three weeks Thursday, the Cubs maintain a five-game lead over Milwaukee as they get ready to host the third-place Cardinals.
"We have a chance to [distance] ourselves from them and they have an equal chance to get closer," manager Lou Piniella said. "It's still a little early in the season, but it would be nice for us to play well against them."
It was nice Wednesday to get some production from Marquis, who may be skipped next week for one turn in the rotation, and DeRosa, who is hitting .355 in his last 10 games and gobbled up eight RBIs in his last two.
"It feels good to contribute," he said. "[For a] guy who takes it home with me, July was a rough month. Even though the team was successful, you still want to be productive and take some of the pressure off some of the big guys, although it doesn't look like [ Alfonso] Soriano needs much help right now. When he gets hot, it's pretty unbelievable."
Yes, Soriano was at it again, hitting a three-run homer in the same inning as DeRosa's slam, a third inning that produced eight runs and quickly erased a 4-1 deficit to give Marquis breathing room.
How did DeRosa cope for the last month?
"You never doubt yourself, you never lose confidence," he said. "You wonder sometimes when you're going to get going. I've always been a streak hitter. I never doubted that I would get hot again.
"But … the team is having so much fun and you don't want to be that guy who is moping in the corner. You try not to be. A lot of flaws are hidden among the teams that have success."
Among the flaws has been the much-maligned Marquis, who actually has pitched much better than his record has shown for the last month.
"I've been through these stretches before. It happens," he said. "You just have to battle, know what you're capable of doing and stay positive."
The Cubs are winning now because of a suddenly red-hot offense that had deserted them during a July swing through Houston and Arizona. The lineup has produced nine double-digit hit days in the last 15 games, including Wednesday, when every starter reached base and scored.
"I said when we were in Houston and Arizona that once we got [a healthy] Soriano back that would help stabilize a lot of things offensively. And it has," Piniella said. "He gives us a lot of flexibility and when he gets hot, he carries you."
Soriano has 20 hits, including six homers, in his last 11 games.