Greenberg, a left-handed hitter who previously played with the Chicago Cubs, was struck in the head in his first ever at bat in 2005. Suiting up for the Cubs, Greenberg was struck in the back of the head by a 92-mph fastball from Marlins left-hander Valerio de los Santos on July 9, 2005.
After being hit, Greenberg was helped from the field and had to be taken to the hospital. He suffered from vertigo following the accident and never made it back to the majors, although he did play a few seasons in the minor leagues.
Greenberg is one of only two players to be hit by a pitch in his first-and-only Major League plate appearance and never take the field, according to The Palm Beach Post. The other is Fred Van Dusen.
"I'm extremely proud to extend this opportunity to Adam," Marlins owner Jeffrey Loria said, according to The Palm Beach Post. "He has earned this chance as his love and passion for the game never diminished, despite his career tragically being cut short. I look forward to seeing Adam step up to the plate and realizing his comeback dream next Tuesday night."
Greenberg will donate his one-day salary to the Marlins Foundation and the Sports Legacy Institute.