Jimmy Rollins and Yasiel Puig opened the first inning with back-to-back doubles for a quick 1-0 lead against John Lamb.
Adrian Gonzalez added a double in the third inning, followed by a two-run shot by Justin Turner to left field, a fly ball that just kept carrying into the seats for a 3-0 advantage.
Lamb was laboring all night. He threw 30 pitches in the first inning, 22 more in the third, and was done after 108 pitches in just five innings. The Dodgers threatened against Lamb in each of his five innings, and if anything probably should have scored more than three runs against him.
Two of Lamb's three major league starts are against the Dodgers, against whom he has struck out 13 in 11 innings. But he also got tagged for nine runs in those 11 innings, and two losses.
Those extra runs came quickly against the Reds bullpen, beginning in the sixth inning against Ryan Mattheus, who got the first two outs of the frame. Alex Wood extended the inning with a single, then Rollins pulled one into the right field seats, 422 feet away for a 5-0 advantage.
It was the 13th home run of the season for Rollins, who was 2-for-4 with a walk on the night.
Before the All-Star break, Rollins had 22 extra-base hits in 339 plate appearances (one every 15.4 PA), with an isolated power number (slugging percentage minus batting average) of .125.
Since the All-Star break, Rollins has 15 extra-base hits in 140 PA (one every 9.3 PA), with an isolated power number of .200. That ISO for Rollins is second on the team since the break, trailing only Turner (.232).
Wood pitched scoreless baseball into the sixth inning on Tuesday, and was even allowed to face Joey Votto in the inning, and got him out. But after a two-out single by Brandon Phillips, Wood was pulled with a 5-0 lead with one on and two outs, having thrown just 88 pitches
Wood, who was pulled mid-inning after 82 pitches in each of his last two starts, tried to plead his case for remaining in the game, but manager Don Mattingly brought in the right-handed Chris Hatcher to face right-handed slugger Todd Frazier.
The matchup numbers favored Mattingly's choice, with Frazier hitting .267/.299/.667 this season against left-handed pitchers and .266/.325/.541 in his career, compared to .255/.321/.449 career against right-handers and .258/.315/.470 in 2015.
But the Dodgers' win expectancy at that point in the game was 97.1 percent, and with just 88 pitches and a five-run lead if there was ever a time to let Wood try to pitch deeper into a game, this was it.
Wood was understandably upset, and threw his glove across the dugout after getting removed from the game. And that was before Hatcher allowed a double down the third base line that managed to carom off Turner's glove, then third base umpire Chris Guccione's leg, and finally the short wall in foul territory in left field, allowing Phillips to score from first base.
Even holding a 5-0 lead at one point, this wouldn't have been a Dodgers game if they didn't at some point face the tying run at the plate. After Hatcher's inherited run scored in the sixth inning, J.P. Howell and Juan Nicasio combined for the next six outs, but Nicasio, in his first appearance after getting activated from the disabled list earlier in the day, loaded the bases in the eighth inning with two walks and a single.
That brought Jay Bruce to the plate as the potential tying run with two outs in the inning, and southpaw Luis Avilan was brought in to face him. Avilan, who last pitched last Wednesday, got the best of the left-handed Bruce in a six-pitch battle, striking him out swinging on a 2-2 curve to end the inning.
With a four-run lead and a non-save situation, Kenley Jansen pitched the ninth to close out the win.
The Dodgers will try to build some momentum in another battle of southpaws on Wednesday night, sending Brett Anderson to the mound in the middle game of the series. The Reds will counter with David Holmberg, who lasted all of two innings against the Dodgers on Aug. 15.
Home runs:(15), Jimmy Rollins (13)
WP - Alex Wood (9-8): 5⅔ IP, 4 hits, 1 run, 3 walks, 4 strikeouts
LP - John Lamb (0-2): 5 IP, 5 hits, 3 runs, 3 walks, 6 strikeouts