Michael Conroy/Associated Press

Al Horford will hit free agency and is apparently not expected to re-sign with the Boston Celtics, according to Steve Bulpett of the Boston Herald.

While it was initially believed he would sign a new three-year deal with Boston, he is now reportedly expected to sign a four-year deal with a new team this summer.

Adrian Wojnarowski of ESPN reported Tuesday the center would decline his $30.1 million option for 2019-20, though both sides seemed to have interest in coming to terms on a new deal.

However, Shams Charania of Stadium and The Athletic reported the Celtics are ready for a "strong scenario" that both Horford and Kyrie Irving will leave in free agency. Irving has sent signals that he's "likely" headed to the Brooklyn Nets, per Charania.

This seems to be a quick change after Bulpett previously reported that "the sides have been discussing a plan where he comes in at a lower number next season and gets two more years tacked on in a new deal."

Still, Zach Lowe of ESPN noted the rest of the league wouldn't just back down:

Boston apparently didn't do enough to convince the veteran to remain with the team:

Horford has spent the past three years with the Celtics, averaging 13.5 and 7.0 rebounds while making an impact that went well beyond the box score. He was an All-Star in 2017-18 and a key part of the team's run to the Eastern Conference Finals that season.

His 7.5 win shares ranked second to Irving (9.1) on the Boston roster in 2018-19, per Basketball Reference.

Now the squad could potentially lose both of them in free agency after failing to acquire Anthony Davis in a trade.

Jayson Tatum, Jaylen Brown and Marcus Smart will help the Celtics contend in the Eastern Conference, but there are serious question marks about the squad going forward.