Returning to the big leagues seven years after he was beaned, Greenberg fanned on three pitches Tuesday night as a pinch-hitter for the Miami Marlins.
Greenberg signed a one-day contract before the game and batted leading off the sixth inning against New York Mets 20-game winner R.A. Dickey.
After Greenberg received a standing ovation from the modest crowd and his teammates, Dickey threw him three consecutive knuckleballs. Greenberg took the first for a strike, then swung at the next two and missed.
The game was Greenberg's first since his major league debut with the Chicago Cubs in 2005, when he was hit in the back of the head by the first pitch he saw - a 92 mph fastball that derailed his career.
The 31-year-old Greenberg took part in batting practice and then watched the early innings from the bench. After Rob Brantly homered, he received a celebratory chest bump from a grinning Greenberg in the dugout.
By the fifth inning, Greenberg had a bat in his hands as he paced in the dugout. In the sixth, manager Ozzie Guillen sent him up to bat for outfielder Bryan Petersen.
He swung under an 80 mph knuckler for strike three, and the crowd groaned, then renewed its cheers as Greenberg walked back to the bench. He smiled as he received a hug and back slaps from Jose Reyes, high fives from other teammates and a whisper in the ear from Guillen.
When Greenberg slipped his bat into the rack, he was still grinning. Guillen replaced him in the lineup before the next inning.
Greenberg said he was overwhelmed by the positive reception from his new teammates, who pledged to treat him like any other rookie. Catcher John Buck said Greenberg would don a USA Speedo, blue tennis shoes and pink goggles for a pregame performance in the clubhouse.
"I've got to go sing and dance in front of them like a real rookie," Greenberg said. "That, to be honest, is what I'm more nervous about."
The 5-foot-9 Greenberg said he hoped the game marks only the beginning of a career comeback. He didn't play in the minor leagues this year and hasn't been with a major league organization since 2008, but he still harbors hopes of a big league job.
Greenberg recently played for Israel in the qualifying round of the World Baseball Classic.
"Hopefully there is going to be a lot more of this. This is good stuff," Greenberg said at a pregame news conference. "I want to show everyone I can play, although you can never really truly do that in one at-bat, especially if it ends up being against Dickey."
Several Marlins played with Greenberg in the minors as he struggled to recover from his beaning.
"He was a good player, and for it to be ruined on one pitch is a tough blow, if you will," Buck said. "But he has fought back. This is one of those good stories for young kids and what baseball is about - enduring to the end, and making the most of your opportunity."
The Greenberg signing was a rare feel-good story for the last-place Marlins, who have endured the most disappointing season in the franchise's 20-year history. They gave Greenberg jersey No. 10, a more prestigious number than the No. 66 he recalled wearing in Cubs spring training.
The outfielder made his big league debut with the Cubs in Miami on July 9, 2005, and was hit by a pitch thrown by Marlins left-hander Valerio De Los Santos. He sustained a concussion that caused vision problems, vertigo and headaches lasting hours at a time, and it was nearly two years before he regained full health.
"I was concerned more with the quality of my life than playing ball," he said. "It was a tough time."
He married, started a health-supplement business and played in the independent Atlantic League. A recent online campaign known as "One At Bat" lobbied for Greenberg to get a second chance in the majors, and the Marlins last week offered him an opportunity to play in the next-to-last game of their season.
For seven years, Greenberg was one of only two players to be hit by a pitch in his lone big league appearance and never take the field. The other was Fred van Dusen with the Philadelphia Phillies in 1955.
Van Dusen flew down from his home in Franklin, Tenn., to attend Tuesday's game. He threw out the first pitch and joined the rest of the crowd applauding Greenberg's comeback.
"Life throws you curveballs," Greenberg said. "Mine threw me a fastball at 92, and it hit me in the back of the head. I got up from it, and my life is great."