Boston Celtics power forward/center Al Horford knows there's a more lucrative deal waiting for him in the free agent market.

According to The New York Times' Marc Stein, Horford knows he can sign a four-year deal worth more than $100 million with another team. That knowledge led to an alleged breakdown in contract negotiations with the Celtics.

Stein's update is consistent with a June 18 update from ESPN's Adrian Wojnarowski. The latter confirms Horford won't exercise his player option worth $30.1 million for the 2019-20 NBA season. This will make him an unrestricted free agent.

Talks on a new deal with the Celtics have perished, with too great of a gulf between what the team is willing to offer and what Horford wants on a long-term deal, league sources said. Horford is entering free agency with the full expectation that his three-year Celtics career has ended, sources said.

Horford, a five-time All-Star, was a key member of the Celtics' core and a favorite of management, coaches, and teammates.

If Horford and perennial All-Star point guard Kyrie Irving leave Boston, the Celtics' playoff aspirations could take a serious hit. Marcus Morris and Terry Rozier are unrestricted free agents. If they leave as well, things will look bleaker. General manager and president of basketball operations Danny Ainge certainly has his work cut out for him.

With the way things are looking, Horford's days in Beantown are numbered. Where will he end up next? It should be interesting to find out.