Updated

Bronson Arroyo pitched six strong innings and homered in the sixth inning for the go-ahead run of the Cincinnati Reds' 3-2 victory over the Arizona Diamondbacks on Monday night.

Brandon Phillips added an RBI double for the Reds, who remained six games ahead of St. Louis in the NL Central and gave manager Dusty Baker his 400th win with the club.

Aroldis Chapman pitched the ninth for his 32nd save.

Justin Upton drove in both runs for the Diamondbacks, who have lost four straight and six of eight during their 10-game homestand.

Arroyo (11-7) allowed two runs and five hits for his fourth straight win.

With two outs in the sixth, Arroyo lofted a pitch from Tyler Skaggs toward the left-field bleachers where it struck a railing and ricocheted to the left and back onto the field.

Umpires, apparently believing the ball had hit the top of the fence initially called the ball in play and Arroyo stopped at second, but after a video review he was awarded his sixth career home run.

Skaggs (1-1), making his second career start, gave up three runs on five hits over 5 2-3 innings. He struck out five, walked two and hit a pair of batters.

Upton gave the Diamondbacks a 1-0 lead in the second with a solo home run to left. The Reds tied the game in the top of the third when Wilson Valdez singled and scored on Phillips' double to center.

Cincinnati added an unearned run in the fourth when first baseman Paul Goldschmidt couldn't handle a throw from Skaggs, allowing Scott Rolen to score from third. Upton knotted the score in the bottom of the inning, singling home Aaron Hill with one out.

NOTES: Chapman has converted a franchise record 24 straight save chances. . Baker is the seventh manager in Reds' history to collect at least 400 wins. . Arroyo's last home run was June 17, 2010 against the Los Angeles Dodgers. . Reds 1B Joey Votto, out with a left knee injury since July 17, did not work out with Class A Dayton because of inclement weather. He's expected to begin his rehabilitation assignment on Tuesday, weather permitting. . RHP Johnny Cueto (16-6) will take the mound on Tuesday night for the Reds against Arizona rookie LHP Wade Miley (14-8). Cueto is tied with Washington's Gio Gonzalez and the New York Mets' R.A. Dickey for the NL lead in wins and leads the NL with a 2.47 ERA. With the trade of Joe Saunders to Baltimore, the 25-year-old Miley is the second-oldest pitcher in the Diamondbacks' starting rotation.