A person with knowledge of the situation tells The Associated Press that prized free agent Al Horford has agreed to terms on a four-year, $113 million deal with the Boston Celtics.

Horford made his decision on Saturday evening after spending most of the first two days meeting with the Wizards, Celtics and the Atlanta Hawks, the team that drafted him. The person spoke on condition of anonymity because the contract cannot be signed until July 7.

Horford, however, made it clear with a simple tweet: “Celtic pride,” it said, followed by 18 shamrocks.

Horford spent his first nine seasons in Atlanta, but the Hawks agreed to terms with Dwight Howard and Kent Bazemore on big-money deals, leaving them little room for their centerpiece. Atlanta could have made a trade or two to create enough room to keep him as well, but by Saturday Horford was already starting to look elsewhere.

The four-time All-Star averaged 15.2 points and 7.3 rebounds for the Hawks last season. He gives the Celtics a formidable presence on both ends of the floor as they try to vault into the top tier of the Eastern Conference.

After Kevin Durant, Horford may have been the most impactful unrestricted free agent who was considered even somewhat available. LeBron James certainly would top that list, but he told media in Cleveland last week that he planned to remain with the Cavaliers after leading them to the championship.

Horford has established himself as the ideal big man for the new era, a versatile player who can shoot from range, move the ball and provide top-notch defense. He has played center with Atlanta but also has the capability to slide to power forward in bigger lineups, giving his coaches multiple options to help them match up with opponents.

advertisement | advertise on newsday

He struggled with injuries in 2011-12 and 2013-14, but bounced back to play 76 games two years ago and all 82 last season as the Hawks emerged as a top-tier team in the Eastern Conference. But as good as they have been in the regular season, they haven’t quite been able to carry it over to the playoffs and so Hawks coach and team president Mike Budenholzer looked to shake up the roster a bit to get the team over the hump.

Budenholzer agreed to terms with Howard to give the Hawks more muscle and interior defense and gave Bazemore a whopping four-year, $70 million deal to remain in Atlanta. He also shipped Jeff Teague to Indiana to open the starting point guard job for Dennis Schroder. They stayed in the hunt with Horford to the very end, hoping to keep him to pair with Howard in what would have been an imposing frontcourt.