PHOENIX -- Cincinnati right-hander Keyvius Sampson is playing his first two weeks in the majors on the installment plan.

"I'm here, just trying to buy more starts," Sampson said. "That's what I'm doing, day by day, just trying to buy more starts."

Sampson (1-1) seemed to assure himself of a third start wth his first major league victory on Saturday, supported by three home runs in the Reds' 4-1 victory over the Arizona Diamondbacks at Chase Field.

Sampson gave up one run and four hits in six innings in his third appearance and second start. He struck out four in six innings but was taking nothing for granted.

"Until they tell me I have a bullpen in two days, I'm still on the bubble in my head," said Sampson, claimed off waivers from the San Diego Padres in the offseason before being promoted to the Reds on July 30.

"For me, I'm always thinking this could be your last one, so you need to go out there and leave it all out there. Of course I'd love to be here, but they have some tough decisions to make."

Shortstop Eugenio Suarez, second baseman Brandon Phillips and left fielder Marlon Byrd homered to back Sampson, who began the season in Double-A Pensacola before being promoted to Triple-A Louisville in mid-June.

Suarez's two-run homer gave the Reds a 2-1 lead in the fourth inning and Phillips hit a bases-empty homer in the fifth. Byrd added a solo homer in the ninth, the 150th homer of his career.

Suarez's homer broke a 30-inning scoring drought for the Reds, their longest drought since going 30 innings without a run April 18-22, 1989.

"Three homers," Cincinnati manager Bryan Price said. "That will do something to end a drought right there.

"Keyvius just pitched a whale of a game. He attacked the zone. Showed great composure. We really liked what we saw in spring training. He had a repeatable delivery and a very solid, consistent demeanor. I think he has the perfect disposition as a starting pitcher."

Left fielder David Peralta had a run-scoring single after center fielder A.J. Polloci doubled for two of Arizona's five hits.

Diamondbacks first baseman Paul Goldschmidt was 0-for-4 and left three runners in scoring position, falling behind Washington's Bryce Harper for the National League batting lead. Goldschmidt, hitting .332, has three hits and one RBI in his last 27 at-bats.

Sampson fell behind Goldschmidt 2-0 with a runner on third and two outs in the third inning but evened the count with two curveballs before getting a strikeout on a fastball. He got Goldschmidt to ground into a first-pitch double play with runners on first and second and one out in the fifth.

"He can't always be the guy that saves us," Arizona manager Chip Hale said of Goldschmidt. "He obviously didn't get the hits tonight, but we always want him up in those situations and we will take our chances."

Left-hander Aroldis Chapman pitched the ninth for his 24th save of the year.

The Reds (49-59) had lost four of five while being shut out three times.

Left-hander Robbie Ray (3-7) allowed three runs and five hits as Arizona (53-56) lost for the third time in five games. Ray struck out eight for the third time in five starts, tying a career high, but gave up homers on off-speed pitchers to Suarez and Phillips.

"It is two pitches that got me tonight," Ray said. "If I could take those back I would."

NOTES: The Diamondbacks retired Randy Johnson's No. 51 jersey in a pregame ceremony, the second jersey retired in franchise history after Luis Gonzalez's No. 20. Johnson spent eight seasons with Arizona, where he won four of his five Cy Young awards. "This is about everyone else, not me," he said, acknowledging former teammates, clubhouse personnel and medical staff. The Diamondbacks presented him with a drum set with gold-plated hardware that is an exact replica of the drum set used by Neil Peart on Rush's 30th anniversary tour. Johnson is a big fan of Rush. ... Cincinnati 1B Joey Votto leads the major leagues with 29 walks since the All-Star break. He has walked 21 times in the last 12 games. ... Arizona traded 2B/SS Cliff Pennington to Toronto for minor-league INF Dawel Lugo, who has spent the entire season at the Class A level. The Diamondbacks purchased the contract of INF/OF Jamie Romak from Triple-A Reno to fill the roster spot. ... Arizona purchased the contract of LHP Phil Hessler to fill the roster spot open after the trade of LHP Oliver Perez to Houston on Friday night. Hessler, an undrafted free agent signed in 2011, pitched a 1-2-3 eighth inning in his major league debut.