BOSTON -- Celtics forward Gordon Hayward left Tuesday night's game against the Brooklyn Nets due to a right knee contusion.

Hayward, who played 17 minutes and had seven points in the first half, didn't come out for the start of the second half, with backup Javonte Green starting in his place. A short time later, Boston announced Hayward was done for the night.

Hayward was hurt when Celtics center Daniel Theis fell back and appeared to hit his shoulder on Hayward's right knee/leg with a little more than two minutes remaining in the second quarter. Hayward grabbed at his knee briefly but remained in the game. He finished the first half without incident.

The Celtics went on to lose 129-120 in overtime.

Kemba Walker, who made his first appearance since the All-Star break after missing five straight games with left knee soreness, also came off the bench in the second half as Boston had him on a strict 20-25 minutes limit in his first game back.

Center Robert Williams, who missed three months because of ongoing hip issues, also made his return, playing three first-half minutes and scoring on a putback on his very first play on the court. He finished with 10 points and three rebounds.

Boston was playing without Jayson Tatum, who sat with an illness. Tatum won his first-ever Eastern Conference Player of the Month award on his 22nd birthday Tuesday. The Celtics have had only 14 games this season where their top five perimeter players -- Walker, Tatum, Hayward, Jaylen Brown and Marcus Smart -- have all been available at the same time.

"Yeah, it is weird," Smart said before the game of Boston's ongoing health issues. "But yet we still been striving all year. It's crazy how well we've been playing with key guys out. It shows us how dangerous we really can be when we have the full roster. That's just something positive that we've got to look forward to having everybody back."