Catcher Ryan Lavarnway had a memorable performance on Tuesday night. (AP)

BALTIMORE — Ryan Lavarnway had long since proven his credentials as a hitter. For three years as a Red Sox minor leaguer, the 24-year-old had demonstrated that he had the makings of a legitimate big league hitter, thanks to both a sound, disciplined plate approach and a compact swing that produced more consistent power than any other Sox minor leaguer.

Even so, there had been skepticism at times about his defense. He was viewed by some as wooden behind the plate — even though he’d worked hard for years to improve his behind-the-plate athleticism. There were questions about his ability to control the running game, even though he’d thrown out 37 percent of attempted base stealers while making just one throwing error in 2011, the top marks among Sox minor league catchers. And then there were the questions about whether he was up to the task of being a signal caller who could earn the trust of a pitching staff.

“It was rumored he wasn’t great defensively but he was a good hitter,” Sox catcher Luis Exposito, Lavarnway’s teammate last year in Double-A and this year in Triple-A, said before the game. “For me, he’s definitely, from what I’ve heard and seen, developed into a good catcher. He’s done the work he’s needed to do. He’s developed himself into this situation where he’s the guy tonight.”

And so he was. Lavarnway, who enjoyed a stint as the Sox DH at the end of August and also spent a few innings behind the plate in the late innings of some games, made his first big league start as a catcher on Tuesday night, at a time when both Jason Varitek and Jarrod Saltalamacchia had been injured.

The result was a singularly impressive performance by the rookie. Lavarnway blasted his first two major league home runs — a three-run blast in the third and a solo shot in the eighth — while making several standout defensive plays and managing the pitching staff to lead the Sox to an 8-7 victory over the Orioles.

It was a night that was in a way surreal, and that Lavarnway — who had played sparingly in September, getting just seven at-bats, mostly in meaningless situations — is unlikely to forget anytime soon.

“It’s like a cross between your dream coming true and fantasy camp,” acknowledged Lavarnway. “It feels like I could wear the jersey with pride, especially a little bit more now that I’ve helped out and am contributing. That’s what I wanted to do when I got here. I didn’t want to just have a September call-up that was meaningless. I’m glad I could help.”

Certainly, the performance was eye-opening. While the impact of his offense was undeniable, fellow catcher Saltalamacchia was even more impressed by the catcher’s work behind the dish.

“He did an unbelievable job,” Saltalamacchia said. “We knew he could swing the bat, that wouldn’t be an issue. And he’s smart. He’s done his homework. We talked to him a little before the game, what to expect out of pitchers. But the way he handled the staff was great, calling timeouts when he needed to to slow the game down, two big plays in the last inning. I couldn’t be more proud.”

Lavarnway threw out Adam Jones on an attempted steal of third base in the second inning. On several occasions, he made what the Sox considered well-time mound visits either to give his pitchers a breather or to get on the same page about signals or pitch selection.

Then, in the ninth, he made a pair of major plays. The first was the biggest, coming with one out, runners and the corners and the Sox clinging to a suddenly uncertain 8-6 advantage.

Matt Wieters hit a dribbler out in front of the plate, up the first-base line. It was a play on which a right-handed pitcher — who has the better angle on the ball — will often make the play. But in this instance, Papelbon was deferring to Lavarnway, who lumbered, grabbed the ball, lost his footing but nevertheless managed to make an accurate throw at first to clip Wieters. While the runner on third scored, the second out of the inning — which kept the go-ahead run off of the bases — was a far greater concern.

“I was going after it, and I looked at Pap to see if he was going to get it or not. The look he gave me was, ‘You’d better field this ball,’ ” Lavarnway said. “I went after it, and I kind of tripped as I was throwing a little bit, but I got the ball to first base.”

“That’s one of the toughest plays,” added Saltalamacchia. “You’re going towards first base, you’re in an awkward position to make the throw, both guys are kind of going for it. It’s a tough play. He did a great job.”

That was true of the entire night for Lavarnway, who became the first Sox player to homer in his first start as a catcher since Danny Sheaffer in 1987, and the youngest Sox with a multi-home run game since Nomar Garciaparra did it at precisely the same age — 24 years, 51 days — on Sept. 12, 1997.

Now, the Sox must decide what to do going forward. In the month of September, entering Tuesday night, their catchers had combined for a .137 average, .180 OBP, .316 slugging mark and .496 OPS, with both Varitek and Saltalamacchia enmeshed in deep slumps.

Saltalamacchia said he had not yet been told who will be starting behind the plate when Jon Lester takes the mound for the Sox on Wednesday, though he made it clear that he will not complain if Lavarnway is in the lineup.

“I just want to win — whatever we’ve got to do to win,” Saltlalamacchia said. “It’s my job to go out there and play when I’m in the lineup. That’s what I’ve done all year.”

Lavarnway, meanwhile, was deferential to his teammate.

“We’re going to put our best nine guys out there every day. … Salty is our starting catcher, so I hope he’s feeling all right. If it’s my turn to go, I’m going to go with all I’ve got,” he said. “If I get to catch Lester tomorrow, it would be a great opportunity I would take wholeheartedly. He’s a great pitcher. I’d do my best to do what I can to help the team win like I did today and stay within myself.”

Whether he gets that opportunity remains to be seen. On Tuesday night, the Red Sox were simply happy to appreciate what the rookie had already done.

“He played his [butt] off. That was exciting,” Sox manager Terry Francona said. “Besides what he did offensively, I thought he ran the game. I thought he had a lot of poise. That was one of the more exciting things to watch. We’ve seen a lot of interesting things here over the years. That was right near the top.”