CINCINNATI -- Pinch-hitter Brayan Pena hit a tie-breaking two-run home run in the eighth inning, and right-hander Homer Bailey pitched eight solid innings, lifting the Cincinnati Reds to an 8-3 victory over the first-place Milwaukee Brewers in the opener of a four-game series at Great American Ball Park.

Third baseman Todd Frazier hit a two-run home run and rookie catcher Tucker Barnhart added his first career homer for Cincinnati (13-15).

Milwaukee (20-9) lost for the third time in five games.

Bailey (2-2) retired 12 of 13 in one stretch before allowing three straight singles, including a two-run double by center fielder Carlos Gomez, which tied the score at 3 in the seventh. He walked one and struck out four.

Brewers starter Marco Estrada walked four of six batters in one stretch, including right-fielder Jay Bruce just ahead of Frazier's two-run blast in the sixth that put the Reds ahead 3-1. It was Frazier's first home run since April 15.

Estrada allowed three runs, all on home runs, walked four and struck out six in six innings.

In the seventh, Milwaukee handed the game to its workmanlike bullpen, which owned the fourth-best ERA among relief staffs in the major leagues.

In the eighth, Pena launched Jim Henderson's first pitch 330 feet into the visitors bullpen in right field to put Cincinnati ahead 5-3.

Henderson (2-1) allowed five earned runs and four hits in two-thirds of an inning.

Right-hander Rob Wooten, fresh up from Triple-A Nashville, walked Frazier with the bases loaded to force home the Reds' sixth run. Left-fielder Ryan Ludwick followed with a two-run single making the score 8-3.

Thursday's game began with center fielder Billy Hamilton making a sensational diving catch on Gomez's line drive to center. Hamilton, who was holding his wrist after the catch, remained in the game but was replaced by Chris Heisey when the Reds came to bat in the bottom half of the inning.

Gomez returned the favor when he made a leaping grab of first baseman Joey Votto's drive up against the center-field wall.

Milwaukee hit Bailey hard in second inning, collecting three straight singles, including a RBI hit by shortstop Jean Segura that put the Brewers up 1-0.

After the rough second inning, Bailey only allowed one hit and struck out two in the next three innings.

The Reds tied the score on Barnhart's first career homer on a 1-1 pitch from Estrada leading off the fifth.

NOTES: Reds CF Billy Hamilton left the game with a sprained third and fourth knuckle on his left hand after making a diving catch in the first inning. He is day to day. ... Reds LHP Aroldis Chapman made his first rehab start for Class A Dayton, throwing 18 pitches, 11 for strikes, with two strikeouts in one inning. ... Brewers 1B Mark Reynolds started in right field for just the fourth time in his career. He had made 20 starts this season before Thursday, including 17 at first base and three at third. ... Cincinnati placed LHP Tony Cingrani on the 15-disabled list with left shoulder tendinitis and recalled RHP Curtis Partch from Triple-A Louisville. ... On Thursday, Milwaukee recalled RHP Rob Wooten from Triple-A Nashville and optioned INF/OF Elian Herrera to Triple-A. ... Brewers 2B Scooter Gennett, a Cincinnati native, turned 24 on Thursday.