CINCINNATI -- The Arizona Diamondbacks needed innings from their starter Friday night, especially after their bullpen logged seven frames the night before.

So, they turned to right-hander Rubby De La Rosa.

"He's the guy who's become our horse," said manager Chip Hale. "We wanted him to go deep. He did a great job."

De La Rosa (11-5) allowed two runs over seven innings, and A.J. Pollock and Yasmany Tomas hit solo homers, lifting Arizona to a 6-3 victory over the Cincinnati Reds at Great American Ball Park.

Arizona (60-61) collected 13 hits while improving to 4-1 this season against the Reds.

Since the All-Star break. De La Rosa has been lights out, going 5-0 with a 2.54 ERA in seven starts. He hasn't dropped a decision since July 12.

"I'm just trying to get ahead and attack the zone," De La Rosa said. "I'm more locked in and focused. Just hitting my spots. I have confidence in my stuff."

Pollock remained red-hot at the plate, going 4-for-5 with a homer, double, RBI and two stolen bases.

"That's a pretty good night, especially with the two steals," said Hale.

Pollock became the first player in the majors this season to reach 30 doubles and 30 stolen bases. It was his fourth four-hit game of the season.

He was denied a club-record-tying seventh consecutive hit in the sixth when Reds third baseman Todd Frazier snared his hard line drive.

Meanwhile, Cincinnati's rebuilding project is off to a rough start.

On Friday, right-hander David Holmberg (1-3) allowed five runs and a career-high 11 hits, including two homers for Cincinnati (51-69), which dropped its seventh straight, dropping into last place in the National League Central.

"We're a team that's been scuffling," said manager Bryan Price. "We want to finish strong to have something to build on for the future."

Reds catcher Brayan Pena went 3-for-4 with two doubles and scored a run on Friday.

He singled and scored on center fielder Jason Bourgeois' single in the seventh to cut the D-backs' lead to 5-2.

De La Rosa exited after 93 pitches, but appreciated the opportunity to get through the seventh.

"I wanted to finish what I started," he said.

First baseman Joey Votto made it a two-run lead with his 23rd home run off left-hander Keith Hessler.

Arizona added an insurance run on third baseman Aaron Hill's sacrifice fly in the ninth.

Brad Ziegler pitched a perfect ninth for his 23rd save of the season and 21st straight, one shy of Greg Olsen's club record.

Pollock, who tied a career high with four hits on Thursday night, belted his 13th home run of the season on a 1-1 pitch from Holmberg to put the Diamondbacks ahead 1-0 in the first inning.

Tomas increased Arizona's lead to 2-0 in the fourth with his eighth homer of the year, a 403-foot blast to center.

It was the seventh home run that Holmberg allowed in five starts.

"His last couple of starts haven't been the same as we saw last year," said Price. "He was erratic. He was making what I call empty pitches."

Later in the fourth, left fielder Ender Inciarte's sacrifice fly made the score 3-0.

Arizona scored twice more in the inning when Reds shortstop Eugenio Suarez had catcher Wellington Castillo's line drive carom off his glove into center, making it 5-0.

That was more than enough run support for De La Rosa who allowed only four hits through the first five innings.

"He had really good fastball command," said D-backs catcher Wellington Castillo. "He was getting ahead with the fastball, using his slider. That was the plan. He made all his pitches."

NOTES: Reds 2B Brandon Phillips missed his second straight start with inflammation in his right biceps tendon. He pinch-hit in the seventh and grounded out. ... Diamondbacks 1B Paul Goldschmidt hasn't homered since July 27 and just twice since June 25. He went 0-for-4 with three strikeouts on Friday. ... Arizona faced its fourth straight left-handed starter on Friday. The Diamondbacks are batting .262 against left-handers, fourth best in the National League. ... Arizona RHP Archie Bradley (shoulder tendinitis) is scheduled to make his next rehabilitation start Sunday for Class A Visalia.