Let the record show that Dustin Ackley's first swing as a Mariner produced an opposite-field line drive — a clean single into left.

Let the record show that Dustin Ackley’s first swing as a Mariner produced an opposite-field line drive — a clean single into left.

OK, it was batting practice, but it still made Ackley feel good.

“That first swing, I didn’t know where the ball was going to go or if I was even going to hit it,” he said with a laugh after taking a round of BP before Monday’s Mariners game. “It was a relief.”

Ackley was in Seattle to officially sign his five-year major-league deal with the Mariners, worth at least $7.5 million.

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As part of the day, Ackley donned a Mariners uniform (No. 13, his college number at North Carolina), held a news conference and schmoozed nervously in the clubhouse with current Mariners. It’s the typical routine for a top draft pick, but this one had a little more scrutiny than usual because of Ackley’s status as the No. 2 overall pick.

Ackley said he didn’t really like all the eyes on his BP session. But despite his admitted nerves, he sprayed line drives all over Safeco Field — a venue he called “sweet. I’ve heard great things about it, but being here, you could really tell.”

General manager Jack Zduriencik said Ackley will stay in Seattle for a couple more days before heading to the M’s training complex in Peoria, Ariz.

“We’re going to try to get him back in baseball shape, and then he’ll matriculate into the Arizona Instructional League, and after that the Arizona Fall League,” Zduriencik said. “From now until the end of the Fall League, he’s going to get a lot of baseball, and then be ready for spring training.”

Asked for his expectations as he starts his career, Ackley said, “I’m really excited to get going. I’m just trying to prepare myself to put myself in position to move as fast as I can.”