BOSTON — Paul Pierce’s NBA career will come full circle Sunday at TD Garden.

Pierce, who’ll retire after this season, will make his final appearance in Boston when his Los Angeles Clippers take on the Celtics. As fate would have it, the veteran forward’s NBA career officially began 18 years ago — to the exact day.

On Feb. 5, 1999, a young Pierce made his Celtics and NBA debut against the Toronto Raptors at the Garden.

Pierce’s promise was on display even then — he tallied 19 points, nine rebounds, five assists, four blocks and two steals in Boston’s season-opening loss. (The 1998-99 NBA season didn’t start until February due to a lockout).

Pierce will close the chapter on his Boston career by starting in Sunday’s game, exactly 18 years later — a fitting coincidence that’s not lost on him.

“You know, 18 years ago (Sunday) was my first game as a starter, and I’m ending that off in 2017 as a starter in the Boston Garden to end my career, last game, on the same day, which is pretty ironic,” Pierce said before Sunday’s Clippers-Celtics game.

“But my whole career, the way I got here and everything ended up is pretty ironic, too. … Things just happen for a reason.”