To fill the gap in the backcourt they traded Paul Westphal to the Phoenix Suns for Charlie Scott, who had averaged more than 20 points in each of the previous three seasons.
Despite an uncharacteristically weak bench, the Celtics finished in first place in their division and the second best record in the NBA this season.
Boston earned a shot at another NBA title by defeating the Buffalo Braves and then the Cleveland Cavaliers in the playoffs.
The Suns trailed by 5 points with less than a minute left on the clock, but Westphal made up the deficit almost single-handedly, sending the game into a first overtime period, which ended in a tie.
John Havlicek's basket with 2 seconds remaining in double overtime gave the Celtics a one-point lead, which Boston stretched to two points after sinking a technical foul.