"It was huge. You look at the scoreboard and see 6-0 Milwaukee, you can't quit in that situation. You got to keep fighting in front of your home fans," DeRosa said after Chicago's 7-6 victory.
With the Reds using a five-man infield, DeRosa grounded a single up the middle that went off closer David Weathers' glove. And when second baseman Brandon Phillips couldn't come up with it, pinch-runner Sam Fuld raced in from third with the winning run.
Aramis Ramirez tied the game with a two-run triple earlier in the inning.
"My mind-set was to get something up and try to get it in the air, and I didn't accomplish that task," DeRosa said. "If David Weathers doesn't get a glove on it, I think Fuld still has enough wheels to get home. So anything for the win. To be honest it didn't matter how I got it done. It was a matter of getting it done."
DeRosa is 10-for-10 against the Reds in his last two games against them -- he also went 5-for-5 on Aug. 16.
"Coming off the road trip, I did not see five hits coming. I've been struggling at the plate," said DeRosa, who was 7-for-35 on the Cubs' last swing "I've been taking it home with me."
Chicago's thrilling comeback victory before a wild crowd of 39,075 at Wrigley Field kept the Cubs in first by one game over Milwaukee.
The Reds protested the game, saying Chicago manager Lou Piniella made an illegal double switch in the sixth inning because he did not go directly to the plate umpire.
Interim manager Pete Mackanin said Piniella crossed the foul line before going to plate umpire Rick Reed. Piniella used a double switch, replacing pitcher Michael Wuertz and catcher Jason Kendall with Geovany Soto and Scott Eyre.
"I think they're wrong. As far as I understand the rule, the manager must go directly to the home-plate umpire to make a double switch. If he does not, and he goes toward the mound and crosses the line, he cannot double switch," Mackanin said. "He has to go directly to the umpire. And I told him I disagreed with his decision, and I was going to protest the game."
Rick Reed, the plate umpire and crew chief, cited a rule that says there is no requirement for a manager to announce a double switch before he crosses the line. He said on a first trip to the mound a manager has the option when to double switch as long as he hasn't called a pitcher into the game.
"We were pretty sure when we allowed Lou to make the switch," Reed said.
The Cubs trailed 6-4 when Ryan Theriot worked out a leadoff walk off Weathers (2-6), and Derrek Lee followed with a single. Ramirez then drove a ball to right-center that center fielder Norris Hopper couldn't reach with a dive, and the ball went all the way to the wall for a two-run triple.
Pinch-hitter Daryle Ward was walked intentionally, and Cincinnati then used five infielders, bringing Hopper in from center field.
DeRosa then hit his sharp grounder that the Reds couldn't handle.
"I just have to make the play. At least get my glove out of the way because it was right to Brandon," Weathers said. "But you don't have time to think about all that when the ball is hit back to you. Just a bad outing."
Weathers blew his sixth save in 36 chances. Will Ohman (2-4) pitched the top of the ninth for the win.
Jeff Keppinger had three hits for Cincinnati, including a double in the sixth when the Reds scored twice to take a 6-4 lead.
Coming off a 6-4 trip, the Cubs weren't sharp at the outset. They missed several catches defensively and got a shaky start from lefty Rich Hill, who allowed four runs and seven hits in 4 2/3 innings with seven strikeouts. They did get homers from Cliff Floyd and DeRosa off Bronson Arroyo, who gave up four runs and nine hits in 5 1/3 innings.
With the game tied at 4, Hopper raced home from first with two outs in the sixth and eluded Jason Kendall's tag, scoring on Keppinger's sinking liner double that Cubs' center fielder Jacque Jones couldn't hold. Ken Griffey Jr.'s RBI single made it a two-run cushion.
Hopper also made a great defensive play.
With a runner at first in the fifth, he raced back and climbed the ivy-covered wall in center to make a great catch and rob Ramirez of extra bases.
Hopper's RBI grounder put the Reds ahead in the third, but Floyd and DeRosa hit back-to-back two-out homers in the bottom half for a 3-1 lead.
Following an error by Lee, who dropped DeRosa's throw from second to first on Hopper's bunt single in the fifth, Cincinnati went ahead 4-3 on RBI singles by Keppinger and Phillips plus a broken-bat, run-scoring forceout by Adam Dunn. With runners at the corners and one out, Dunn beat the replay throw as the Cubs attempted a double play. Piniella argued the call with first base umpire Tim Timmons, and replays were inconclusive.
Jones' RBI single tied it in the fifth.
- Keppinger, who also walked, missed the cycle by a homer.
- Alfonso Soriano doubled in the sixth but unwisely tried to go to third on a grounder to shortstop and was thrown out easily.