The Reds look to complete a three-game sweep by handing the Diamondbacks a sixth straight loss Wednesday at Chase Field.
Johnny Cueto threw seven solid innings to become the majors' first 17-game winner and Aroldis Chapman converted his 25th consecutive save as Cincinnati (79-52) won its third straight over Arizona, 5-2 on Tuesday. Winners in three of four overall, the Reds increased their division lead over St. Louis to seven games.
Cincinnati's last series sweep at Chase Field came Aug. 17-19, 2010.
The Diamondbacks (64-66), who dropped to 2-7 on a 10-game homestand, are in danger of matching their season high with a sixth consecutive defeat. Arizona is third in the West, 8 1/2 games behind first-place San Francisco and is 7 1/2 out of the final wild-card spot.
Todd Frazier, one of four Reds with two hits, had a key two-run triple in the eighth inning to break open a one-run game.
"We were just up the one run so that little cushion was helpful,'' Frazier said.
Playing regularly in place of injured star Joey Votto, Frazier is batting .486 (17 for 35) with 12 RBIs during a 10-game road hitting streak. However, the versatile Frazier appears to be headed to the bench with Votto expected to return to action this weekend. He could see time at third base, first base and left field when Votto, Scott Rolen and Ryan Ludwick need a day to rest.
Mat Latos (10-4, 3.84 ERA) takes the mound for Cincinnati trying to rebound after he could not hold a 5-2 lead and was roughed up for seven runs in five innings of an 8-5 loss to St. Louis on Friday.
"I went from having good command of my fastball to not,'' said Latos, who was 3-0 with a 1.49 ERA in his previous six starts.
Though the right-hander is 1-0 with a 1.42 ERA in three starts at Chase Field, Latos gave up five runs and two homers to Jason Kubel in 4 2-3 innings of a 7-1 home defeat to the Diamondbacks on July 18.
Those home runs came in Kubel's only two official at-bats versus Latos. The veteran outfielder gave Arizona a 1-0 lead with a first-inning sacrifice fly Tuesday, but he is batting .158 with 27 strikeouts in his last 27 games.
Arizona rookie Patrick Corbin (5-5, 3.91) makes his sixth straight start since being recalled from Triple-A Reno on Aug. 1. The left-hander went seven innings twice to win his previous two starts before he gave up four runs and nine hits in four innings of a 5-0 loss to San Diego on Friday.
"He didn't have very good stuff,'' Arizona manager Kirk Gibson said. "He wasn't locating well. His pitches were up.''
Corbin will be the third straight rookie to start for the Diamondbacks in this series. Tyler Skaggs and Wade Miley took losses in the first two games.