SAN DIEGO -- Games don't usually swing on a visit to the mound by a pitching coach shortly after a three-run, first-inning homer.

But that's what Cincinnati manager Bryan Price and starting pitcher Raisel Iglesias believe happened Wednesday afternoon at Petco Park as the Reds defeated the Padres 7-3 to prevent a three-game series sweep.

Iglesias had just walked Padres left fielder Justin Upton after serving up a game-tying, three-run bomb to right fielder Matt Kemp when Reds pitching coach Jeff Pico trotted to the mound.

"Jeff really helped settle that environment down," Price said. "From that point on, I mean, Iglesias was unflappable."

Iglesias (3-4) retired the last 16 Padres he faced and departed with a 4-3 lead -- thanks to Padres starter James Shields balking in the tiebreaking run in the third -- to improve to 3-4. Iglesias allowed three runs, three hits and a walk with eight strikeouts in six innings, and Cincinnati's bullpen gave up only two more hits in the final three innings.

"After I gave up that home run, I actually got really disappointed with myself and I lost control of my emotions," Iglesias said through a translator. "I cannot explain how bad I was.

"(Catcher Brayan) Pena and the pitching coach came out and they both started telling me, 'Hey, calm down and don't let emotions come in and start to screw up your game ... concentrate, do what you have to do.'

"You saw what happened."

"It was one of those defining moments," Price said of the first-inning meeting. "He worked his way through it and gave us five scoreless innings afterwards."

"He was impressive,” Padres manager Pat Murphy said of Iglesias. "He pinpointed his fastball down and away. Young pitchers often struggle in the first. He weathered that and got on a roll."

Offensively, Reds first baseman Joey Votto was 3-for-4 with a two-run homer in the ninth off Padres left-handed reliever Frank Garces. Votto's 20th homer of the season carried 404 feet. He also scored three runs (one on Shields' third-inning balk) and stole a base.

Right fielder Jay Bruce had a two-run triple for the Reds.

Meantime, Shields (8-5) suffered his fifth loss in his last six decisions since starting the season 7-0 and seemed to be frustrated in both the first and decisive third innings. The Padres are 2-10 in Shields' last 10 starts.

The Padres are 0-6 in the third game of possible sweeps since completing their only sweep of the season May 1-3 against Colorado at Petco Park.

The game settled down after a wild start.

Cincinnati scored three times in the top of the first off Shields, marking the third time in his last four outings that he has been scored upon in the first. The Padres matched the Reds with Kemp's three-run homer in the bottom of the first.

Reds center fielder Billy Hamilton opened the game by hitting a fly to left that fell in front of Upton for a single. Reds shortstop Eugenio Suarez was then hit by a Shields pitch. Votto, who grounded into a double play Tuesday night in an identical situation, dropped a RBI single into right center, scoring Hamilton, who at first hesitated rounding third.

After Shields struck out third baseman Todd Frazier, Bruce hit a long high drive to center that got over the head of retreating Padres center fielder Will Venable for a two-run triple that made it 3-0.

Shields avoided further damage by striking out left fielder Marlon Byrd and retiring Pena on an inning-ending grounder to second.

The Padres quicky tied the score and missed a golden opportunity to take the lead.

Iglesias hit Padres third baseman and leadoff hitter Yangervis Solarte with a pitch in the right ribs and then gave up a single to first baseman Yonder Alonso. Kemp followed with a 374-foot drive into the first rows of seats in left center for his 12th homer of the season but his first since July 24.

Upton then drew the walk, but Iglesias picked off Upton just ahead of catcher Derek Norris' double down the line in left. Venable grounded out to third to end the threat.

Venable was the first of 16 straight Padres retired by Iglesias, one of five rookie pitchers in the Reds' rotation, before he departed for a pinch hitter in the sixth.

Meanwhile, Shields balked home the go-ahead run in the top of the third.

With one out, Votto singled and raced to third on Frazier's double. While pitching to Bruce, Shields made a motion to third but didn't throw the ball, allowing Votto to score on the balk.

"It was a miscommunication," Murphy said. "We had a pickoff play on, but Solarte didn't see the signal."

Bruce walked and stole second. But Shields struck out Byrd (for the second time) and second baseman Ivan De Jesus (after intentionally walking Pena) to get out of the inning and start a run of 10 straight Reds retired before Brandon Phillips singled off Shields to open the seventh while pinch-hitting for Iglesias.

After two walks sandwiching a sacrifice bunt, Phillips scored on a sacrifice fly by Frazier off right-handed reliever Shawn Kelley.

Shields allowed five runs, six hits and four walks (two intentional) with seven strikeouts in 6 1/3 innings.

NOTES: The Padres had a 4-2 margin in the season series against the Reds. ... About 200 friends and members of Colin Rea's family were at Petco Park from Cascade, Iowa (population 2,200) for his major league debut on Tuesday night. After getting the win, in addition to his first major league hit, Rea spent more than 30 minutes posing for pictures down the right field line with his party. ... Reds manager Bryan Price said he could soon move rookie RHP Michael Lorenzen to the bullpen as a way to limit his innings rather than shut him down in September. He said several other rookie starting pitchers could face a similar limit. ... Padres manager Pat Murphy said INF Cory Spangenberg, who has been on the disabled list since the end of June with a bone bruise to his left knee, is close to returning from his rehab assignment.