CINCINNATI -- Austin Kearns broke out of a slump with a career-best performance.
"I didn't see this coming," said Kearns, who had one hit in his last 18 at bats going into the game. "I don't know. The first couple of innings, nothing was really happening, and then it was just like it opened up. Guys were getting ahead in the count and not missing pitches."
A night after squeezing out four runs on five hits, the Reds set a season-high for runs in a game and in an inning with 10 in the fourth.
"I think winning that ballgame (Thursday) with only five hits gave the guys confidence to go out and swing the bats," interim manager Jerry Narron said.
Felipe Lopez added a three-run homer and Wily Mo Pena had a solo shot for the Reds.
The Reds had 15 hits while winning consecutive home games for the first time since beating Chicago on July 21 and Milwaukee on July 22.
The Diamondbacks have lost five of their last six.
Brandon Claussen went 6 2/3 innings to earn his fourth consecutive win in five starts. He improved to 8-8, yielding four hits and three runs with four walks and six strikeouts.
The Reds sent 12 batters to the plate in the third while matching their season high for hits in an inning with six. Lopez led off with a triple and scored on Rich Aurilia's sacrifice fly. Ken Griffey Jr. and Adam Dunn singled to set up Kearns' first home run.
The Reds added runs on Lopez's bases loaded walk and Aurilia's single, which knocked Arizona starter Russ Ortiz out of the game.
Ortiz (4-7) was making his second start since coming off the disabled list. He gave up seven hits and six runs with five walks and three strikeouts in 2 2/3 innings, his shortest outing of the season.
"He put us in the position of trying to get through the game without burning up the bullpen," Arizona manager Bob Melvin said. "I'd say this is the low point of the season, but every time we've been there, this team has come off the mat."
Ortiz, who was on the disabled list with a stress fracture in his right rib cage, is 0-5 in his last seven starts.
"It's deflating to give up that many runs, but we have to put it behind us, and I know these guys will," Ortiz said.
The Reds sent 14 batters to the plate in their 10-run fourth, which included Lopez's second homer in two days, and 18th of the season, and Kearns' second homer of the game and 11th of the season. Edwin Encarnacion added a two-run single and Sean Casey and Jason LaRue each had run-scoring singles as the Reds again collected six hits.
"The last two or three days, I've been getting pitches to hit, but I was pulling off maybe a hair," said Kearns, whose second homer went to the opposite field. "It was nice to hit one the other way. I was just trying to relax, really. In Milwaukee (last weekend) and even against San Francisco, I was just missing. It's easy to start trying harder. I was just trying to relax and put an easy swing on it.
"I don't think I've ever been a part of anything like that."
Narron was relieved to see Kearns get going.
"He was just trying to drive it to the big part of the ballpark and get one, and he ended up getting all three," Narron said.
The last time the Reds scored as many as six runs in two innings of the same game was on Sept. 4, 1999, when they scored nine in the fifth and six in the eighth of a 22-3 win at Philadelphia. They last scored 10 runs in an inning on Aug. 5, 2004, in the eighth inning of a 12-3 win at San Francisco.
Arizona scored its runs in the fourth on Conor Jackson's bases loaded walk and Luis Terrero's two-run single.
Griffey extended his hitting streak to six games with an opposite-field double into the left field corner on a 3-0 pitch in the first. ... Aurilia extended his hitting streak to six games. ... Kearns snapped an 0-for-13 slump with his first homer. ... Arizona's Royce Clayton extended his hitting streak to eight games. ... The Reds last scored 17 runs in a 17-4 victory at Montreal on Aug. 26, 2001.