Irving missed the end of the regular season and all of the playoffs after having surgery in April to remove screws from his left knee that had been placed in a 2015 procedure to fix a broken kneecap.
Boston's season ended with Sunday's 87-79 loss to the Cavaliers in the Eastern Conference finals.
Smart, 24, is valued for his elite play on the defensive end of the court and his leadership skills, and many teammates referring to him as the "heart" of the team.
That should make it no surprise that Smart is excited for Game 7, and he expects a real dogfight, and maybe for some blood to even be lost.
ESPN sportscaster Mark Jackson was not happy that Celtics point guard Kyrie Irving was nowhere to be found at the TD Garden Sunday night. They have arguably the best coach in basketball at the helm in Brad Stevens. I have a much stronger memory and remember how great those guys were and what an effort it took us to get them. But listen, we need Marcus. If there ever was a team that would know that, it would be this team that just went through what we went through this year to lose two All-Stars in the prime of their careers, early in the season in one case.
Hayward missed all but five minutes this season, his first with the Celtics, as a result of the injury.
According to Ainge, Hayward's latest surgery was due to pain "in one little spot", and it was done to ensure he could return fully healthy for next season.
"I get a kick out of the fact that everywhere I go, people don't think we need Kyrie or need Gordon Hayward", he said. Also, I think it will be Cleveland last National Basketball Association final for a while, on the other hand, Golden State I don't think it will be going anywhere for a little while especially in a Playoff run. And he'll progress along that line slowly. "We need Marcus. Marcus is a good player", Ainge said during an interview with Boston radio station 98.5 The Sports Hub.