Fisher played 18 seasons in the NBA before he replaced the fired Mike Woodson in June. The Knicks went 37-45 last season and missed the playoffs, just a year after winning the Atlantic Division and advancing to the Eastern Conference semifinals.
Boston shot 48 percent from the field and made 11 of 22 3-point attempts.
Sullinger scored eight points in the fourth period as the Celtics pushed their lead as many as 27.
Smart, who missed all eight of his field-goal attempts in his team's preseason opener, was 4 for 8 from the field and had six assists. He was selected by Boston with the sixth overall pick in this year's draft.