BOSTON—Before Friday’s opener against the Red Sox, Orioles manager Brandon Hyde thought his designated hitter might be uneasy.

“We have Ryan Mountcastle, who’s never played in front of fans before in the big leagues,” Hyde said. “You try to remind them this is the same game they’ve played their entire lives on a little bit different stage, and it’s on TV.”

If Mountcastle was unnerved, he didn’t show it. After an impressive preview, in which he hit .333 in 35 games with five home runs and 23 RBIs, the 24-year-old, who’s still eligible for Rookie of the Year honors because he fell four at-bats short of the 130 at-bat maximum, is eager to prove last year wasn’t a fluke,

In 2020, a season in which fans weren’t allowed to attend games because of the pandemic, Mountcastle played left field in 23 games, was the first baseman in nine and the DH in two. This year, with Trey Mancini back after missing 2020 because of colon cancer surgery, Mountcastle might be the DH more often.

On Friday, his two-run, sixth-inning double gave the Orioles their first runs of 2021 on the way to a 3-0 Opening Day victory over the Red Sox before 4,452 fans. John Means, who allowed only one hit in seven standout innings, was the star. Trey Mancini, who had a walk and a hit in his first game back, was the feel-good story. But it was Mountcastle, whose double was kept in the park by Fenway’s Green Monster, who was the offensive hero.

“I thought he hit that ball out,” Hyde said. “To contribute the way he did and put a really nice swing to give us the lead and break the ice for us …

“Opening Day is special for everyone. When it’s your first one, it’s something you’ll remember for the rest of your life. When you produce the way he did, it was an incredible moment for him, and big for us.”

A lifelong Floridian, Mountcastle was looking forward to the first Opening Day game, even if it was 37 degrees at game time.

“Yeah, I haven’t played in weather like this much in my career,” Mountcastle said. “I’ve got to get used to it at some point, I guess.”

Mountcastle had his stepfather, younger brother, girlfriend and her family for support. And even though he wasn’t able to socialize freely with them because of health and safety protocols, the restriction didn’t bother him.

“I’ve gone to big league spring training four or five times, and I’ve gotten sent down every time,” he said before the game. “The first time I get to break with the club, it’s definitely a surreal moment, something I’ll cherish for sure.”

Last year was a fun ride for Mountcastle. This year might be more difficult.

“They’re going to do their scouting reports and all that stuff,” Mountcastle said. “They’re going to try to do whatever they can to get me out. It’s up to me whether I want to adjust or not. That’s part of the game.”

Hyde is confident that Mountcastle will be up to the challenge.

“He is a threat when he swings the bat,” Hyde says. “He has a middle-of-the-field approach and understands how to stay on the baseball, which he does the majority of the time. He’s very, very dangerous because he’s athletic, he’s got great hands, he’s got huge power, and he’s going to have to make adjustments this year.

“I’ve seen a lot of good, young players come into the league and have two good months, and then it’s tough for a while. That’s absolutely normal. I don’t want to put too much pressure on him. I think he’s going to have ups and downs this year like most good, young players do. But I really believe in the ability, and I really believe in the upside, and I think he has a chance to be a good player in this league for a long time.”

Means, who retired the last 18 batters he faced after a leadoff hit by Kiké Hernández, is impressed.

“He’s a special talent,” Means said. “He’s got a great mentality for this game. I don’t think any moment is too big for him. He stays within himself. You’re going to be seeing this kid for a long time.”

Mountcastle has been talked about for a long time in the Orioles’ organization. From the time he was drafted as a shortstop in 2015, Mountcastle struggled to find a position. He was moved from short to third base, then to first base and left field. Last September he got to play in Fenway and played left field in front of the Green Monster.

“Anything over your head is off the Monster,” Mountcastle said. “You’ve got to play it off the wall. It almost feel like you’re in the shortstop’s back pocket playing out there because it’s so shallow, too. I wouldn’t say it’s too difficult, but it’s definitely different.”

He’s now comfortable in left, as he is with the chatter that he can win the American League’s Rookie of the Year award.

“I’ve just got to go out there and play my game,” he said. “If I do that, I think I have a pretty good shot at getting it. I’m not really going to press to win any awards.”

Hyde chose to put him in the cleanup position at designated hitter on Friday. Mountcastle didn’t let him down.

“He’s a young kid that’s played a month in the big leagues, and he’s hitting fourth in the American League East, and because he’s got poise, because he’s got confidence, this guy is going to be a really good hitter in this league,” Hyde said.