Grant Williams, who became a key player for Boston last season, is in the final year of his rookie contract, with the deadline for an extension coming on Oct. 17.

Smart, the reigning NBA Defensive Player of the Year, has helped the 20-year-old second round pick learn the ropes.

Blake Griffin was signed to help fill in the void left by an injuries to Robert Williams III, Danilo Gallinari and Luke Kornet.

Griffin, who played for the Brooklyn Nets last season, could help fill in at center for the injured Robert Williams.

Boston enters a new season with a new coach, but Jayson Tatum and Jaylen Brown are still on hand to lead a team that reached the NBA Finals last season.

Malcolm Brogdon was a top scoring option in Indiana but knows that his role will change with Boston and is willing to sacrifice for the sake of the team.

“It’s a good thing to just play basketball. That’s what we’re here for. It’s important to just start this thing back up again,” said Celtics veteran Al Horford.

Joe Mazzulla addresses reporters on the on the eve of training camp, just a few days after head coach Ime Udoka was suspended for the season.

Udoka is being penalized because he engaged in an improper relationship with a member of the organization, sources say.

Gallinari, who signed with Boston in July, was injured playing for Italy in a FIBA World Cup qualifier.