Hayward - who made his first appearance in over a month in Game 3 of the conference finals due to a severe ankle sprain - contributed six points, five rebounds, four assists, and three steals in 30 minutes off the bench in his return. The forward hadn't played since Boston's opening game of the postseason against the Philadelphia 76ers on Aug. 17.
In addition to allowing key players like Hayward and Kemba Walker to get closer to full health, Smart believes the extended layoff will serve as motivation for a hungry Celtics squad.
"The longer that we have to sit here knowing that we're down 2-1, it's just more fuel to the fire that we know we've got to come out and win Game 4," Smart said.
Smart was speaking for the first time since Boston's reported locker room feud after the team's Game 2 loss to the Miami Heat last week. He took the time to label the incident as something that helped the Celtics grow.
"We're a family. Families fight. ... It happens between families, especially a family like ours who's been together for so long," Smart said, per The Boston Globe's Gary Washburn.
Game 4 between the Celtics and Heat is set for Wednesday at 8:30 p.m. ET.