The Celtics are hopeful that Hayward could play a role off the bench in Game 3, sources told ESPN's Adrian Wojnarowski.
Hayward has not played since Game 1 of the Celtics' first-round series against the Philadelphia 76ers after suffering a Grade 3 right ankle sprain.
The Celtics said at the time of the injury that he would miss "approximately four weeks." Heyward was injured Aug. 17, just over four weeks ago.
Boston trails Miami 2-0 in the best-of-seven series.