SAN DIEGO -- A.J. Pollock's first career grand slam landed in the perfect spot at Petco Park.

Instead of ending up as a souvenir for a fan, the ball was tucked safely in Pollock's locker after he helped lead the Arizona Diamondbacks to a 6-3 victory over the San Diego Padres on Friday night in Casey Kelly's first big league start in just under three seasons.

Pollock's slam sailed an estimated 427 feet to straightaway center, into an area accessible only to the grounds crew and just down a set of steps from the bullpens. Diamondbacks bullpen catcher Mark Reed went over and fetched it.

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"He looks after me," said Pollock, a first-time All-Star this season. "Someone will want it. Someone will think it's cool that it's a grand slam ball."

Pollock also drove in a career-high five runs, all in his first two at-bats.

"He's had a great second half," manager Chip Hale said. "He's probably been our hottest hitter the last month and a half."

Kelly, acquired along with three other players in the deal that sent Adrian Gonzalez to Boston in December 2010, last started for the Padres on Sept. 27, 2012. He underwent reconstructive elbow surgery on April 1, 2013.

He made four minor league starts last year and 31 appearances in the minors this year, including 17 starts, before being recalled from Triple-A El Paso on Sept. 14. He pitched two innings in relief last Saturday.

Kelly (0-1) allowed six runs and six hits in five innings, struck out one and walked one.

"It was such a great feeling," Kelly said about being back. "I was so excited to be able to come out and start at home after such a long time."

Hale said the Diamondbacks put together a scouting report on Kelly based on his one relief appearance for San Diego last Saturday, and from players who faced him in the minor leagues late last year and this season.

Kelly was roughed up early, allowing three straight hits with one out in the first, including Pollock's RBI single and Paul Goldschmidt's run-scoring double.

It got worse in the second. Kelly hit Brandon Drury with a pitch leading off the inning and allowed singles to Ender Inciarte and Phil Gosselin before Pollock hit his slam an estimated 427 feet to straightaway center field. It was his 19th homer overall.

"Bases loaded, one out, you're just trying to find something to get in the outfield and score that one run," Pollock said. "I was just trying to get it elevated in the outfield and get the first run. I was fortunate enough to get them all."

Kelly then retired his final 11 batters.

"After the first tough couple of innings I felt like I settled down and started to work the ball down and really started some offspeed pitches," Kelly said. "Every outing you are going to have some tough things go on but try to take the positives out of it and try to keep moving forward."

Arizona's Rubby De La Rosa (14-8), who underwent Tommy John surgery on Aug. 9, 2011, reached a career high in wins. He allowed three runs, two earned, and four hits in 5 2/3 innings. He walked three and struck out two.

Brad Ziegler pitched the ninth for his 28th save in 30 chances, and 26th straight, the longest active streak in the majors.

Wil Myers and Alexi Amarista hit RBI singles for the Padres.

TRAINER'S ROOM

Arizona: INF Nick Ahmed remains out with a sore lower back.

San Diego: 3B Yangervis Solarte was out of the lineup with a sore right hamstring.

UP NEXT

Arizona: RHP Jeremy Hellickson (9-10, 4.73) is scheduled to start the middle game of the series. He's 1-3 with an 8.37 ERA in five starts against San Diego this season.

San Diego: LHP Robbie Erlin (0-1, 21.00) is scheduled to start for the Padres.