Al Horford was a prime free agent catch for the Boston Celtics three seasons ago, marking the beginning of their ascent toward Eastern Conference contention.

After a surprisingly turbulent season that ended in a five-game “gentleman’s sweep” at the hands of the Milwaukee Bucks in the Eastern Conference semifinals, Horford will reportedly be attempting to boost a division rival over the top.

As first reported by ESPN’s Adrian Wojnarowski, Horford has agreed to a four-year, $109 million deal with the Philadelphia 76ers. The deal includes $97 million in guarantees and $12 million in bonuses tied to championships, Wojnarowski reports. The Celtics, per ESPN, were willing to offer Horford a four-year deal, but he opted for more money.

His was one of at least 11 deals worth at least $100 million agreed to on Sunday, one of the wildest spending days in league history.

Last season, the 33-year-old Horford averaged 13.6 points, 6.7 rebounds, 4.2 assists and 1.3 blocks, shooting 53.5 percent from the field and 36.0 percent from deep — right in line with his career averages even as he played a career-low 29.0 minutes per game. The 12-year veteran again made the playoffs, maintaining a perfect record of reaching the postseason to cap each campaign he’s played in the league.

A versatile big, the 6-foot-10 Horford can easily slot at either the 4 or 5, adept at playing in multiple offensive styles as need be. In Philadelphia, he’d slot alongside All-NBA center Joel Embiid — who stands 7-foot — and Tobias Harris (6-foot-9) in a towering front line that should present matchup problems and difficult decisions for opposing defenses.

Information from The Associated Press was used in this report.