But for Greenberg, Tuesday didn't mark the actualization of a dream seven years in the making. It marked the start of what he hopes is another opportunity to achieve a bigger, lifelong goal.
"This is the start. This is realizing Day 1 of that dream I had seven years ago and had as a child," Greenberg said minutes after signing his one-day contract with the Marlins. "Right now, hopefully this is the start of my career in this game that I wanted as a kid. I feel like I'm going to show it, not in one at-bat, but this is the start of hopefully Part 2 of my career, and that's what I'm most grateful for."
Greenberg, 31, made his big league debut with the Cubs on July 9, 2005, against the Marlins in South Florida. But in his only plate appearance, he was hit in the back of the head by the first pitch he saw -- a 92 mph fastball from Valerio de los Santos.
The outfielder became just the second player in Major League history to get hit by a pitch in his only plate appearance and not record an inning in the field, joining Fred Van Dusen, who did so for the Phillies on Sept. 11, 1955. Van Dusen was also a special guest at Marlins Park on Tuesday.
As a result of the pitch, Greenberg suffered a concussion, had vertigo and dealt with vision problems -- problems that still bother him to this day.
He never made it back to the Majors. That is, until Tuesday, when the Marlins gave him a chance to get his one at-bat
Greenberg's at-bat, and the opportunity that essentially was taken away from him seven years ago, finally came in the sixth inning, when he pinch-hit for Bryan Petersen to lead off the frame while the Marlins held a 2-0 lead against knuckleballer R.A. Dickey.
Greenberg walked out to the plate to a standing ovation from the 29,709 in attendance and settled into the batter's box.
"It was magical," Greenberg said. "The energy that was in the stadium was something I never experienced in my life, and I don't know if I'll ever experience that again."
He looked at the first pitch Dickey offered, a knuckleball down the middle of the plate. He swung at the second pitch and stepped out of the box to take a breath. The third pitch fluttered past Greenberg, who swung and missed, striking out in his first official Major League at-bat.
Greenberg's at-bat lasted just 33 seconds, but to him, it will last an eternity.
"That's 33 more seconds than I could have asked for," he said.
When it was over, he walked back to the dugout, where Jose Reyes greeted him with a hug at the top step, while the crowd at Marlins Park gave Greenberg another standing ovation.
"This kid brought a lot of smiles, a lot of tears," Marlins manager Ozzie Guillen said. "The team's in last place, and all of a sudden you see a standing ovation in the ballpark. You don't see that often, and that was great."
Despite being 0-for-1 with a strikeout in his only career at-bat, Greenberg was all smiles in the dugout, basking in the moment and rekindling a lifelong dream.
"I couldn't be more happy with how it's turned out," Greenberg said. "I don't care what's gone on in my seven years; it's all worth it for this moment."
Greenberg's road back to Tuesday's moment wasn't an easy one. He signed Minor League contracts with the Royals and the Dodgers in 2006, and one with the Angels in '08. He played in the independent Atlantic League from 2008-11.
"[He was] a guy who was battling to get back to the big leagues like everybody was at Double-A, but his situation was unique," said Justin Ruggiano, who was Greenberg's teammate and road-trip roommate in 2006 with Double-A Jacksonville. "He was grinding extra hard that year."
Greenberg's quest back to the Majors, and to get one at-bat, was spearheaded and documented by filmmaker Matt Liston. Liston's efforts created a viral movement via social media.
Last week, Marlins president David Samson called Greenberg and told him he deserved the opportunity, and the sides agreed to a one-day contract. The team transferred infielder Nick Green to the 60-day disabled list to make room for Greenberg, who prepared for his chance and tried to approach it like any other game, although it certainly wasn't.
Five innings after Greenberg's at-bat, the Marlins walked off thanks to a Donovan Solano single in the 11th. Greenberg hopped the fence of the dugout and sprinted toward first to hug Solano.
On this day, no one was going to beat him there.
After the game and the celebration on the field, Greenberg took a curtain call and got one last standing ovation from the fans who stuck around for the outcome, finally bringing his night -- but hopefully not his dream -- to an end.
"It proved to me once again that as a kid, this is what you want," Greenberg said. "This is what you hope for -- to play Major League Baseball. ... That's something I got to experience tonight, and I don't ever want to forget that. I want to come back next year and continue this journey and start my career again."
Tom Green is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.