In his first at-bat with the Portland Sea Dogs, Josh Reddick dug into the batter’s box and lined a 1-1 fastball into right field.

The crowd at Hadlock Field in Portland, Maine, erupted — as David Ortiz, the Boston Red Sox designated hitter and fan favorite, trotted home with a run. But as the 21-year-old Guyton native stepped to the plate for his first at-bat in Class AA, his only thought was the oft-repeated mantra of South Effingham High School coach Tony Kirkland:

“Do your job.”

“My mindset was it was just another at-bat,” Reddick said. “Just get the pitch you want and drive it.”

Ortiz, the slugger with a penchant for clutch hits, was in Portland on a rehab assignment, reporting the same day (July 21) Reddick was promoted. He got to the park ahead of the regular Sea Dogs but spent 30 minutes talking about hitting with the Red Sox of the future.

“It wasn’t a big deal to me. It was another run,” Reddick said of his first regular-season RBI for Portland. “You’ve still got to go out and prove yourself. It was the bottom of the first. We had eight more innings to play.”

But for Reddick, the remainder of his stay in Portland and the Eastern League was more difficult. Promoted after hitting .343 with 17 homers and 57 RBIs at high Single-A Lancaster (Calif.), Reddick hit .214 in 24 games in Portland. He finished with six homers and 25 RBIs.

Portland was his third stop of the season after starting the season in Greenville (S.C.), where he hit a cool .340 in 14 games prior to the call up to Lancaster. But the difference from A ball to AA?

“Huge,” he said. “It was a lot more different than I thought it would be.”

The biggest change was the opposing pitchers and it wasn’t just their stuff was better. They also had an idea of what they wanted to do on the mound.

“In high-A, you’ve got those guys who will put it wherever they want to,” Reddick said. “Other guys are like, all right, here’s my fastball. I’m going to try to blow it by you if I can.”

Pitchers — and hitters — use more video on each other and rely more on in-depth, detailed scouting reports.

“They make that adjustment to get you out,” Reddick said. “As a hitter, I never made the adjustment back to get into a better position to hit. My body was tired. I didn’t take into account what I needed to do to go up there and adapt to that kind of pitching.”

Reddick’s baseball season didn’t end with Portland’s loss to Trenton — the New York Yankees’ Double-A affiliate — in the Eastern League playoffs. The young man went west to play in the Arizona Fall League with the Scottsdale Scorpions. He hit .189 with five homers and drove in 15 runs in 23 games.

As one of the Red Sox’s top minor league prospects, Reddick went to Boston earlier this year for a series of clinics and to meet top Sox brass, including manager Terry Francona and general manager Theo Epstein. Reddick didn’t get a taste of how frenzied Red Sox Nation can be, but he got a taste of something else.

“It was the first time I’ve seen snow in my life,” he said. “It was a lot different atmosphere.”

Besides taking cuts in the indoor batting cage at Fenway Park and learning how the big club looks at video, there were twice-a-day sessions on the other parts of life that go with being a big leaguer.

Club officials gave the minor leaguers lessons on life in Boston — what to do and what not to do, what to say and what not to say with the Boston media, how to stay comfortable and what to expect while you’re there.

“We were hit in every direction with everything we got,” Reddick said.

The prospects also took part in an event for the Jimmy Fund, the children’s cancer organization that has been a mainstay of the Red Sox community outreach for decades. Because of the cold, there wasn’t a lot of interaction with the fans, but they knew some of the club’s most highly-regarded prospects were in town. First baseman Lars Anderson, Reddick’s teammate at Lancaster and Portland and the Sox’ top prospect, and pitcher Daniel Bard drew the most attention.

“We didn’t get to see the full throttle thing up there,” Reddick said.

A 17th-round pick in 2006, Reddick is also considered among Boston’s best prospects and his name frequently appears in discussions among Red Sox minor leaguers in the Boston papers and fan blogs. Not that he would notice.

“I don’t go out and look for it,” he said. “It would just make my head bigger, and I don’t really need that. But my mom will call me or my dad will call me and Coach Kirkland will call me, hey, check this out. Of course, it’s always good to get your name out there.”

In just two years, pro baseball has taken Reddick from South Carolina to Maine, back to South Carolina, to California, to Maine again and to Arizona — not to mention spring training in Florida.

Reddick said having good friends and good family in Effingham, and good teammates and friends on the team, helps him stay grounded. He calls his parents every other day and Coach Kirkland every other day.

If he’s struggling at the plate, no matter the mileage or time zone difference, he doesn’t have to tell them much for them to let him know what to correct.

“They know exactly what I’m doing, even though I’m not there,” Reddick said. “It’s like having a mental coach right there in your head.”