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2/21/2013 12:14 P.M. ET

O'Sullivan aims to seize opportunity for homecoming

San Diego native hoping to parlay non-roster invite into Opening Day roster spot

PEORIA, Ariz. -- When Sean O'Sullivan closes his eyes, he can still see Tony Gwynn peppering the "5.5 hole" between shortstop and third base during batting practice. And he can still imagine Steve Finley reaching over the center-field wall to rob opposing batters.

O'Sullivan, a native of El Cajon, located just east of downtown San Diego, played Wiffle ball following Padres games in the parking lot of Jack Murphy Stadium, which was later called Qualcomm Stadium. He's so old school that he still refers to it as "The Murph."

In fact, many of O'Sullivan's best memories as a child revolve around going to Padres games with family, which is why it will be such a big thrill Friday (12:05 p.m. PT) when the right-hander gets a start for the team in its game against the Mariners at the Peoria Sports Complex.

"I was a Padres fan as soon as I knew what baseball was," said O'Sullivan, who is in big league camp as a non-roster invitee. "When I came into the offseason as a free agent, I knew if this opportunity presented itself, I was going to take it."

O'Sullivan, 25, is likely to throw two innings against the Mariners. He wore a Padres uniform for the first time on Monday for photo day, though this will feel significantly different.

He is a Padre, at last.

O'Sullivan, who graduated from Valhalla High in El Cajon, spent all of last season in Triple-A. He went a combined 14-7 with a 4.23 ERA in 31 games, including 19 starts, for Omaha and Las Vegas. He was a lot better with Las Vegas, going 9-3 with a 2.72 ERA in 14 starts.

"I didn't feel like I could be beat," O'Sullivan said of his time with Las Vegas.

But there have been times when he's gotten away from what serves him best -- pounding the strike zone. That was the case in stints with the Angels and Royals from 2009-11, when he posted a 10-14 record and a 6.13 ERA in 43 games (34 starts).

"My biggest thing is attacking the zone early," said O'Sullivan. "It's when I try to get too cute with my pitches that I start to go off the rails. When I attack the zone with ferocity, that's when I'm at my best."

Winning a spot in the rotation won't be easy. The Padres have no fewer than 10 candidates trying to win a job in the rotation. The good news for pitchers like O'Sullivan is there will be ample chances to do so, as the team will play a club-record 38 exhibition games before Opening Day on April 1.

Could O'Sullivan crack the rotation?

"The thing that stood out for me when I saw him this winter at Petco [was that] he looks in great shape," said Padres manager Bud Black. "[He's] really determined to make his mark. He's been with a couple different teams with some varied success, but there is a determined look in his eye, which is great."

O'Sullivan, who said his preference is to start, could offer the team a versatile arm moving forward should he make the Opening Day roster. If that happens, it will be a dream come true for the Rancho San Diego resident and his family.

"I'm happy with what I'm doing right now, where I'm at and knowing if I make the team, I can go home to my team," he said. "That opportunity would be priceless."

Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.