PEORIA, Ariz. -- Every Major League journey starts somewhere, and for Justin Dunn, that moment began Wednesday as he took to the mound for his first bullpen session at his first big league camp.

With general manager Jerry Dipoto, manager Scott Servais and much of the Mariners' brass watching intently, the highly regarded 23-year-old from New York had a chance to make his first impression since being acquired from the Mets as a key part of the return in the Robinson Canó Edwin Díaz trade.

"It was a little nerve-wracking, obviously my first time up," said Dunn, a right-hander with mid-90s heat and solid off-speed offerings. "I have a lot of expectations on myself and to see all those guys around, it's getting close to decision time and I'm fighting for a job, at least in my head. I always put that expectation on myself. But it was good to get out there and feel healthy and strong."

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Dunn is likely ticketed to start the season in Double-A Arkansas. He's wearing jersey No. 62 and sitting at the far end of the Mariners' clubhouse reserved for non-roster invitees. But he's the Mariners' No. 3 ranked prospect by MLB Pipeline and figures prominently in Seattle's future plans.

For now, he's "trying to be seen and not heard" while soaking up knowledge from the veterans and coaches in camp.

"It's very cool to look across the locker room and see [ Félix Hernández ] and Mike Leake , guys I grew up watching," he said. "It's kind of a surreal moment. But I'm excited. I'm just listening to everything and trying to learn as much as I can."

Dunn's fastball showed plenty of life in his first outing, though he wasn't cranking full throttle yet despite the natural adrenaline rush for the former Boston College standout. Overthrowing on the first day is definitely not the way to go in the first step of a long season.

"It wasn't 100 percent, but I definitely didn't back off at all," he said. "I more went off feel. It's still early, so I'm working on mechanical stuff and getting my pitch breaks down and getting those to feel comfortable. Then as I get comfortable, I'll add some intensity along the way."

Position players rolling in

With position players due to report on Friday, many of the Mariners are already in camp as Mitch Haniger and Ryon Healy were the latest to check in on Wednesday.

Among the veteran position players not in camp yet are Edwin Encarnacion , Daniel Vogelbach , Dee Gordon , Kyle Seager and Ichiro Suzuki .

The 26 position players will take physicals on Friday prior to the first full-squad workout on Saturday.

Bautista brings it early

Among the many youngsters in camp, Gerson Bautista features the highest velocity with a fastball that's been clocked at 100-101 mph. Acquired from the Mets in the same trade with Dunn, he'll be an intriguing prospect to watch if he can add some deception to that heater.

Catcher David Freitas said the 23-year-old showed some pretty good off-speed offerings as well in his initial bullpen outing, which bodes well for a youngster ranked No. 28 on Seattle's MLB Pipeline prospect list.

"Our scouts and our analytical people like his off-speed pitches a lot," manager Scott Servais said. "There's a lot to like, and he throws really hard. It's a good frame. It's a wiry, whippy body. It's exactly what you are looking for. There's plenty to work with there.

"I think that's what excites our coaching staff as much as anything. There's a lot of clay to mold in this group. The guys with that kind of ability, you are always excited. Hey, what can this guy be if this clicks or if we make this kind of adjustment? Often times that's just what it is. It's one or two things, and they take it and run with it."

Last group of pitchers goes Thursday

Hernandez and closing candidate Hunter Strickland will highlight Thursday's bullpen sessions, which will conclude the first round of throwing for all 32 healthy pitchers in camp.

Yusei Kikuchi drew considerable attention with his first bullpen outing on Wednesday, alongside veteran Mike Leake.

The final group will take the mounds off of Field 3 at the Peoria complex starting about 11:40 a.m. MT on Thursday, though rain is in the forecast and those sessions could be moved to the covered bullpens adjacent to the facility if needed.