PHOENIX — Another win for Cincinnati. Another hero for the Reds.

On Thursday night, it was catcher Ramon Hernandez, who with Jay Bruce hit back-to-back homers in the fourth inning to break a scoreless tie and Cincinnati beat the Arizona Diamondbacks 9-5.

The victory gave the Reds a three-game sweep over the NL West cellar dwellers, and was Cincinnati’s sixth straight win overall, the team’s longest streak of the season.

The Reds took a season-high 3 1/2-game lead over the St. Louis Cardinals for first place in the NL Central and won their seventh straight road game.

Hernandez, on a .360 tear with two home runs since coming off the disabled list on July 22, blasted a three-run shot to left field on the first pitch he saw from Joe Saunders (7-13). Bruce followed with his second homer in as many nights. It was the seventh time the Reds hit back-to-back homers this season.

“I haven’t been thinking that I was injured,” Hernandez said. “I get ready the same way and try to stay patient and wait for the pitch I’m looking for. Nothing more than trying to make good contact with the ball and I’m being aggressive in the strike zone. … I don’t try for home runs.”

Travis Wood, called up from Triple-A Louisville on Thursday to join the starting rotation for the time being, lasted 6 1-3 innings and allowed one run and four hits with six strikeouts. Wood (4-1) lowered his ERA to 2.51.

“Everything was feeling pretty good,” Wood said. “We’re playing well right now. Three here, we’ve got tough games in L.A. coming up, so hopefully we can carry it over and just keep moving on with it.”

Hernandez’s homer drove in Scott Rolen, who had walked, and Jonny Gomes, whose single put runners at first and third with one out.

The Diamondbacks made it 4-1 on Mark Reynolds’ 27th home run in the bottom of the fifth.

Saunders gave up four runs and eight hits over six innings and lost his third straight game in his fifth start with Arizona.

Saunders, dealing with flu-like symptoms, gave up four runs and eight hits over six innings and lost his third straight game in his fifth start with Arizona.

“It is a simple fact that I made two bad pitches,” Saunders said. “I should have known that Ramon was going to be aggressive with runners in scoring position. … It wasn’t a bad pitch, just probably the wrong pitch.”

The Reds added the rest of their runs in the eighth after a two-out fielding error by Diamondbacks’ left fielder Rusty Ryal, who dropped what should have been the third out after making a catch. A walk and pinch-single by Laynce Nix followed, then another walk and Drew Stubbs’ two-run single.

“Rusty made the error. The guy busts his tail every day and we have to pick him up,” Diamondbacks manager Kirk Gibson said. “Sometimes it seems like we are far away but really not. When you play a team like this and they are on a roll like this, it can be disappointing.”

The Reds (70-51) put five runs on the board in the eighth, capped off with Joey Votto’s two-run double. Votto was back in the lineup after missing Wednesday’s game with a sore back.

The Diamondbacks had a four-run eighth that included a three-run home run by Chris Young.

Notes: To make room for Wood, the Reds optioned RHP Carlos Fisher to Triple-A Louisville. Fisher’s designation meant that rookie Mike Leake, who has started 22 games but struggled in his past two, was moved to the bullpen. Manager Dusty Baker said Fisher will get a September call-up. … The official scorer changed what was ruled a sacrifice fly and RBI for Nix on Wednesday in the eighth inning to a fly out with no RBI and an error on Arizona RF Justin Upton for an overthrow of home plate. Hernandez scored on the play.