SAN DIEGO -- Through an interpreter, Luis Perdomo quickly and succinctly answered an obvious question with one emphatic word.

"Was this your best start of the year?"

"Yes," said the 23-year-old rookie right-hander, who four short months ago was struggling to find his major league bearings as a Rule 5 long-man in the San Diego Padres bullpen.

Sunday afternoon at Petco Park, Perdomo took a shutout into the seventh inning and finished by allowing one unearned run on five hits and no walks with five strikeouts as the Padres defeated the Arizona Diamondbacks 9-1.

Perdomo also had a run-scoring double as he and San Diego's all-rookie outfield gave the Padres a third win in a four-game series between two teams that entered the weekend set tied for last in the National League West.

--Right fielder Patrick Kivlehan, who was 2-for-4 with a homer in his major-league debut Saturday night, reached base in all four of his plate appearances Sunday and scored three runs. Kivlehan was 2-for-2 with two walks Sunday making him only the fourth player in franchise history to have multiple-hit games in his first two major-league games. The only other Padre to reach base six times in his first two major-league games was Anthony Rizzo in 2011.

--Center fielder Travis Jankowski broke a scoreless tie with a two-run homer in the third to stretch his string of reaching base to a 20th straight game. It is the longest active streak in the National League and the second-longest active streak in the major leagues.

--Left fielder Alex Dickerson hit his eighth homer of the season.

But Perdomo was the story as he has been most of the second half of the season.

Since moving permanently into the Padres' rotation on June 15, the Dominican Republic native has lowered his earned run average in 10 of his 12 starts. Sunday, his ERA fell from 6.68 to 6.24 as he improved to 6-7.

Sunday marked the second time Perdomo went seven innings. It was only the third time in his 14 starts that he didn't walk a batter.

"He's made huge strides," Padres pitching coach Darren Balsley said of his prized pupil. "He doesn't want to just be here. He wants better. When he comes to the dugout after an inning, he doesn't want to hear how good he's doing, he wants feedback.

"He's very unique . . . very easy to work with."

"Perdomo was outstanding," said Padres manager Andy Green. "He attacked hitters all day. That's the best breaking ball he's had. And his sinker was working . . . very effective at getting outs."

Meanwhile, Arizona starter Braden Shipley (2-3) didn't fare as well. After a strong start, Shipley gave up seven runs on seven hits -- including the Jankowski and Dickerson homers -- in 5 1/3 innings.

"It looked like he had really good stuff," said Arizona manager Chip Hale of Shipley. "Jankowski's homer came on a pitch up and in that wasn't a strike. Then he issued that walk and began falling behind hitters."

Jankowski gave Perdomo all the runs he needed with his two-run homer in the third. Kivlehan opened the bottom of the third with a single. With two outs, Jankowski drove a 1-1 pitch from Shipley 395 feet into the right-field stands for his second homer of the season -- and his first ever at Petco Park.

Perdomo had a hand in the Padres' production in the fifth when they widened their lead to 4-0.

Kivlehan drew a one-out walk -- the only walk issued by Shipley -- and scored on Adam Rosales' triple to right-center. Perdomo then pulled a line drive into the left-field corner for a run-scoring double.

The Padres scored three more runs in the sixth.

Dickerson opened the inning by golfing a changeup from Shipley 394 feet into the right-field stands. With one out, Christian Bethancourt singled and scored on a double by Brett Wallace. Kivlehan singled home Wallace.

A throwing error by Perdomo led to Arizona ending his shutout bid in the top of the seventh.

With one out, Phil Gosselin topped a ball between the mound and third. Perdomo threw wildly to first, allowing Gosselin to reach second. He scored on Brandon Drury's two-out single.

After Padres' right-handed reliever Kevin Quackenbush struck out the side in the eighth, the Padres added two final runs.

Kivlehan drew a one-out walk from reliever Patrick Corbin and reached third on Rosales' double. Both scored on a two-run single by pinch-hitter Alexei Ramirez.

NOTES: Padres CF Jon Jay hit off the tee for the first time Sunday since going on the disabled list June 28 with a fractured right forearm. The Padres are hoping he will return during the first week of September after a rehab assignment. ... RF Jabari Blash missed a fifth straight start with a jammed ring finger on his right hand, leaving the Padres without a pure spare outfielder. ... Diamondbacks 1B Paul Goldschmidt singled in the third inning Sunday to extend his streak of reaching base against the Padres to 12 games.