CINCINNATI -- San Diego manager Bud Black used the word "maddening," while his reigning Cy Young Award-winning pitcher Jake Peavy opted to use the phrase "frustrating" on Tuesday.

No, Black and Peavy weren't trying to sum up San Diego's overall play and state of affairs through the first 101 games, though they wouldn't be far off if that were indeed the case.

Instead, Black and Peavy were referring to the sixth inning at Great American Ball Park, an inning that was every bit as decisive in the Reds' 4-3 victory in 11 innings as the last inning, when Jeff Keppinger's RBI double to left field won the game.

It was the sixth inning when Peavy, staked to a 3-0 lead, allowed three runs, two walks, three hits and what amounted to a wheel barrel's worth of bad luck, thrown together in the Reds' three-run inning that left Peavy feeling remorseful.

"That was frustrating. I've got to make a pitch to get out of that inning," Peavy said after the game, not long after Keppinger's game-winning hit off reliever Bryan Corey allowed Jay Bruce, running on the play, to score from first base.

"I've got to make a pitch to get my team out of the inning. I do and we win the game."

Instead, Peavy and the Padres (38-63) were left to kick around their 19th one-run loss of the season.

Peavy took a four-hit shutout into the sixth inning having not faced more than five batters in any one inning. He was working quickly, got ahead in the count and, even for a power pitcher, appeared as if he had pitch-to-contact on the brain.

But in the sixth inning, Peavy walked Ken Griffey Jr. and allowed a single up the middle to Brandon Phillips. Peavy then appeared to catch a break when he got Adam Dunn to hit a ground ball directly at second baseman Edgar Gonzalez.

But Gonzalez was slow to get rid of the ball, and while his throw to shortstop Khalil Greene was in time to get Phillips at second base, the play took long enough to develop that the 275-pound Dunn beat the return throw from Greene at first.

"The ball had top spin and it came up on me," Gonzalez said. "I was playing him a little more in the hole [between first and second base]. I was trying to make a good throw. He ran pretty hard down the line."

This would prove important later, as, following a Javier Valentin out, Peavy walked Edwin Encarnacion after getting ahead in the count with two quick strikes. Catcher Paul Bako, who entered the game hitting .213, bounced a two-run single up the middle.

Finally, pinch-hitter Joey Votto tied the game at 3 with a check-swing single to left field that allowed Encarnacion to score.

"It was maddening," Black said. "That [hit by Bako] was a seeing-eye three-hopper and Votto stuck his bat out."

Five Cincinnati pitchers, beginning with starter Johnny Cueto, combined to strike out 18 Padres, one short of San Diego's season high, which was also against the Reds, though that came on May 25 in an 18-inning game.

Cueto, the hard-throwing 22-year-old right-hander, struck out 10 in six innings and only allowed three runs, all coming in the third inning when Brian Giles had a two-RBI double and Adrian Gonzalez followed with an RBI single.

The Padres' bullpen trio of Mike Adams, Heath Bell and Cla Meredith combined for eight strikeouts over four shutout innings after Peavy left after the sixth inning. Corey came in the game to start the 11th inning.

Black was especially pleased with Meredith's two shutout innings that came with four strikeouts. Black talked to Meredith on Monday about making a few adjustments, as far as pitch selection and mechanics, and the submarine-style pitcher put them to use.

"That's the Cla we need to see," Black said.

Corey, who allowed a game-winning grand slam to St. Louis' Aaron Miles on Sunday, allowed a one-out single to Bruce. Then, on a full-count pitch and with Bruce going on Corey's delivery, Keppinger lined a ball into the left-field corner to win the game.

It was the Reds' Major League-leading 10th walk-off victory of the season.