Arroyo (10-7), who gave up both runs while striking out four and walking none, retired the first 14 batters before Domonic Brown's two-out homer in the fifth. Brown doubled off the wall in right-center with one out in the eighth and pinch-hitter Kevin Fransden reached on an infield single leading off the ninth for the other hits off Arroyo.
Other than that, the Phillies didn't have anything close to a hit off Arroyo, who was 0-6 with a 9.46 ERA in his last seven regular-season starts against the Phillies. But Arroyo has been hot lately, improving to 6-1 with a 3.50 ERA in his last seven starts.
Aroldis Chapman relieved Arroyo after Fransden's hit. Fransden went to second on Chapman's wild pitch and scored on pinch-hitter Ty Wigginton's one-out single to right. Wigginton's broken bat caromed into the back of Chapman's left leg and the lefty limped around but remained in the game after a visit from the trainer. Chapman then got Chase Utley to fly out and Ryan Howard to line out sharply to left for his 31st save in 35 chances.
Run-scoring singles by Drew Stubbs and Ryan Ludwick in the fifth inning off Philadelphia starter Vance Worley staked Cincinnati to a 2-0 lead.
Worley (6-9) allowed two runs and eight hits in six innings. It was Worley's third straight loss but the longest outing in four starts for the righty, who has one win in his last seven starts.
Brown launched Arroyo's first pitch - a 90 mph sinker - deep into the seats in right field for his first homer of the season and eighth in 324 career at-bats.
Bruce led off the eighth and gave the Reds a 3-1 lead with a towering homer off the concrete wall below the second deck in right off right-handed reliever Josh Lindblom.
Brown lost Bruce's pop fly in the lights in the fourth inning, leading to a triple. But the right fielder made two strong defensive plays, a full-out sprinting dive to his right to rob Arroyo of extra bases in the second and an excellent throw to nail Bruce at the plate trying to score on Todd Frazier's medium fly ball in the fourth.
Philadelphia got two runners on base in the eighth when Placido Polanco followed Brown's double by reaching on third baseman Scott Rolen's fielding error. But the Reds ended the inning with a sensational double play on Brian Schneider's grounder up the middle. Shortstop Zack Cozart ranged behind the bag at second, fielded with his glove and flipped to Brandon Phillips. Phillips jumped and caught the ball, then spun in one motion for a one-hop throw to first that was cleanly picked by Frazier.
Notes: The Reds are 27-11 without Joey Votto, who has been on the DL since July 17 with a left knee injury. . After winning seven straight against the Reds, Philadelphia has lost two straight to Cincinnati. . On Retro '90s Night, the Phillies wore maroon and white pinstriped uniforms from the 1991 season. . Phillies lefty Cole Hamels (14-6, 2.94) is scheduled to face Cincinnati righty Johnny Cueto (16-6, 2.44) Thursday night in the conclusion of the four-game series.