CLEVELAND – Celtics forward Gordon Hayward left Boston’s season opener against the Cavaliers with a gruesome leg injury Tuesday night. Hayward, making his Celtics debut, elevated for an alley-oop early in the first quarter and landed awkwardly on his left leg. His foot appeared to twist to a 90-degree angle.

Boston announced that Hayward had a fractured left ankle.

Reaction to the fall was instantaneous. Referees immediately called a timeout. Celtics and Cavs medical staff rushed on the floor. Players recoiled, stunned. Dwyane Wade took a knee. LeBron James leaned against the scorer’s table, praying. An emotional group of Celtics players hugged each other on the opposite end of the floor. A capacity crowd — energized for the return of Kyrie Irving — stood hushed.

Hayward remained on the floor for several minutes. His leg was placed in a sleeve, and he was carted off the floor on a stretcher. Players from both teams rushed to Hayward’s side as he was carted off the floor.

On social media, other players responded quickly. Paul George — who suffered a horrific leg injury of his own in 2014 — tweeted his support. James rushed back to the Cavaliers locker room during a timeout to check on Hayward, who was later moved to the Celtics locker room.

Hayward, 27, signed a four-year, $128 million contract with Boston this offseason.

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