The Celtics, who are the favorites to win the NBA title this season, now have almost their entire core under contract for next year. The lone exception is forward Grant Williams, who was unable to agree on an extension before the October deadline and will become a restricted free agent in the summer.
League sources have said the Celtics plan to keep Williams in the fold, and if the sides are unable to reach a deal, the team would likely match any offer sheet that Williams signs with another team anyway.
https://www.bostonglobe.com/2022/12/01/sports/al-horford-celtics-agree-two-year-extension/