SAN FRANCISCO -- As the frenetically upbeat opening notes of Banda MS' "El Mechón" blared from the speakers in the top of the seventh inning, the tension that had been building since the first pitch was released in a rapid crescendo as the crowd leapt to its feet and clapped along to the beat, chanting "Romo! Romo! Romo!" when it faded out from the speakers.

It was a fitting last dance for Sergio Romo, who took his time to savor the moment as he jogged in from the bullpen.

"I'm thankful for it all," a glassy-eyed Romo said, "just blown away."

Romo's storied career -- one that has spanned 15 seasons, eight big league teams and three World Series rings -- came to a fitting end during Monday night's 12-6 loss to the A's. The 40-year-old right-hander signed a Minor League deal on March 18 in order to retire as a Giant, an honor he couldn't have imagined back when he was selected by San Francisco in the 28th round of the 2005 Draft.

"To … try to accept the fact that this is something that a lot of people felt that I deserved -- it's mind-blowing to me," Romo said. "I'm still kind of struggling with that. The reception I got just running out to the bullpen, the reception I got running out on the mound, walking off.

"It's hard to not think that it's a dream, but very fitting way to walk out, very fitting to find some closure in what literally is for me … a storybook career."

The last active member of the Core Four relievers who helped power the Giants to three championships in five years from 2010-14, Romo spent nine seasons with San Francisco, going 32-26 with a 2.58 ERA and 84 saves in 515 games. He made a franchise-record 27 playoff appearances for San Francisco, most notably striking out the side -- freezing Tigers great Miguel Cabrera with a fastball -- to secure a sweep in the 2012 World Series.

"So deserving of the honor of walking off this field a Giant," said manager Gabe Kapler. "Such an incredible contributor to the history of this franchise."

But when current and former teammates think of Romo, his vibrant personality outshines even his best moments on the mound.

"I think the thing with Sergio Romo is that it doesn't really matter who you are -- you play with him, you're staff, you're media, whatever -- he's pretty much the same person to everybody," said Giants left-hander Alex Wood, who was briefly Romo's Dodgers teammate in 2017. "I think he's an extremely kind, energetic, fun person. He's got a little bit of crazy in him."

That smattering of crazy showed up throughout Romo's career, from his starring role in the Giants' "Mi Amor" commercials to his "Romo-bombing" antics during TV reporters' live hits.

"A big part of Sergio is wanting to have fun, either in the dugout or in the clubhouse or something like that," said Brandon Crawford. "But once he gets on the mound, he's super competitive, and he's gonna give you everything he's got out there."

That was no different on Monday night. After facing three A's batters, all of whom reached base, he received a surprise mound visit from none other than former teammate Hunter Pence. Romo hugged Pence, handed him the ball and stepped off the mound to a warm ovation from the fans, who had remained standing from the time he entered the game.

Romo took a sweeping look around Oracle Park, cracking a wry smile as he strolled to the dugout. There, he exchanged hugs with his coaches and teammates before again doffing his cap for the crowd when he returned to the field for a heartfelt curtain call.

The appreciation for Romo wasn't exclusive to those clad in orange and black. Romo, who suited up for the A's in 2021, received plenty of love from the opposing dugout before and during Monday's game.

"He deserves every minute of it," A's manager Mark Kotsay said of Romo's sendoff. "He's given his life to baseball, to that Giant organization."

Romo doesn't know exactly what's next, but he's not quite done being around the game. He'll travel with the Giants to Mexico City next month as a team ambassador, and he looks forward to having more time to spend with his wife and five sons. If it were up to him, a stint as a pro golfer would be in the cards as well.

Before all that, Romo will need a little time to soak in his final moments on the field.

"That's it, man. No more for me," he said. "I can honestly say that I'm proud to acknowledge the fact that, not just tonight but my whole career, I emptied the tank. I gave it everything I had every time, if it went well, if it went poorly -- I never hung my head because I gave it what I had that night."