BOSTON — Amid a growing rivalry between the Celtics and Hawks, Al Horford formed a close relationship with a Boston sports icon.

Horford, who grew up in the Dominican Republic, has been a fan of Red Sox slugger David Ortiz for years. The feeling was mutual. Ortiz watched Horford’s father, Tito, play in the NBA and was excited for the younger ball player to make it to the NBA.

After the two were told of each other’s mutual admiration, they met during Horford’s rookie season at TD Garden. They have developed a friendship over the past two years, and Horford even visits with Ortiz whenever the Hawks come to Boston.

“I know that since I’ve been there, the last two days he’s been at Fenway working out, that’s all I can say,” Horford told WEEI.com on Friday.

Horford always respected Ortiz’s game, and this week he saw his work ethic firsthand.

“It looks like the season just got over and he’s already getting back to work,” Horford said. “So that speaks a lot about him.”