BOSTON -- For 14 years, David Ortiz has been known throughout Fenway Park as "Big Papi."

On Monday, he revealed he's also a proud papa.

By all accounts, Ortiz has held it together in the early stages of his final big-league season. The iconic Boston Red Sox slugger was reflective, but not overly emotional, during spring training and already has made it through a few highlight videos on ballpark scoreboards without welling up.

On the occasion of his final Fenway Park opener, though, Ortiz was reduced to tears when his 15-year-old daughter, Alexandra, surprised him by singing the national anthem, which she had been practicing with her chorus teacher while Ortiz was away in Florida for spring training and on a week-long season-opening road trip to Cleveland and Toronto.

"It was a surprise, a beautiful surprise," Ortiz said later, after closer Craig Kimbrel allowed a three-run homer to Chris Davis in the ninth inning of a 9-7 loss to the undefeated Baltimore Orioles. "At some point, you start thinking about your kids and the way you raise your kids and everything that you've been through. I got caught into those memories, and it was beautiful."

Ortiz's family was seated on folding chairs on the warning track behind home plate when the Orioles and Red Sox were introduced at sold-out Fenway Park, leaving Alexandra skeptical that her father wouldn't figure out her plans to sing. But Pedro Martinez's wife, Carolina, came to sit with her, tricking Ortiz into thinking they were simply there to get a prime view of the pregame pomp.

As Alexandra sang, Ortiz "started a little bit crying," according to first baseman Hanley Ramirez, who was standing alongside him on the first-base line. And when she was through, Ortiz came over to give her a hug.

"He said to me, 'Don't ever surprise me like that again,'" said Alexandra, the second oldest of Ortiz's three children. "I wanted him to be emotional. Somebody told me that he cried, and I was like, 'Yes!' I didn't know if that was a terrible thing."

The Red Sox made sure Ortiz was surrounded by Boston sports legends for his final Fenway opener. He joined Bobby Orr, Bill Russell and former New England Patriots cornerback Ty Law in throwing out ceremonial first pitches and made the customary "Play Ball" announcement with former Red Sox teammates Martinez, Jason Varitek and Tim Wakefield.

Then there was a game to play. Ortiz drove in a run with a wall-scraping single in the first inning and lined a two-out double off the Green Monster in the seventh. He had a chance to give the Red Sox a walk-off victory in the ninth when he came up in a two-on, none-out situation against Orioles closer Zach Britton. But with a chance to write an ending that even a Hollywood director would find overly saccharine, he grounded into a double play.

"I can only speak for what went through my head, and it was a like a fate-destiny thing -- his last home opener, what a way to end it," said leadoff man Mookie Betts, who already had homered off Britton, one of his three hits to snap a 3-for-23 funk. "I was fully confident in his ability to hit it out of the park as well as hit a base hit. He hit the ball well, and they were able to make a diving play."

Rest assured, Ortiz will have other opportunities to win a game for the Red Sox before he calls it quits, and the most clutch hitter in franchise history likely will come through in a few of those spots.

But hearing his daughter sing the national anthem before 37,160?

That's once-in-a-lifetime stuff.

Alexandra isn't as much of a presence around Fenway as her brother, 11-year-old D'Angelo, who tags along with his father at every chance and even played a prominent role last year on a baseball show for kids that airs on the New England Sports Network. As she walked on the field before the pregame ceremony, Alexandra said she teased her brother about reaching his level of stardom.

"I was like, 'There, now we're even. Now we're good,'" she said. "It feels good, but I love him. Yeah, I'm pretty proud of myself. My mom said she was proud of me. I was pretty proud."

Alexandra's musical talents are evident, Ortiz said, when she sings around the family's house in suburban Weston. Her favorite genre of music? "A lot of blues, like older music, anything honestly. You could probably name them, and I would like it," Alexandra said.

And if her performance on Monday was any indication, there's music in her future.

"I was more nervous during that time than during any at-bat I've ever had in my career," Ortiz said. "It wasn't even about me. It was about her. Whoever has kids knows how that goes, when you're watching your kid perform in anything. That was like my first big moment watching one of my children just doing something pretty big. Now I understand my dad and my mom and my family when they used to watch me. They all used to be very nervous. Now I get it. It was unbelievable. She came through."

At Fenway, of all places. Just like her father.