Cavaliers 102, Celtics 99: Celtics’ Gordon Hayward Fractures Ankle in Season Opener

CLEVELAND — Less than six minutes into his first game as a member of the Boston Celtics on Tuesday, Gordon Hayward badly fractured his left ankle on a failed alley-oop attempt.

The injury, which happened during the N.B.A.’s season opener, was a crushing blow to the Celtics in their quest for Eastern Conference superiority. Hayward, a forward who signed a four-year, $128 million contract with the Celtics in July, had been slotted into a roster with Al Horford and Kyrie Irving in a new Big Three for a team that has been on the rise for the last several seasons.

“It’s a tough, tough deal,” Celtics Coach Brad Stevens said. “But I guess that’s part of it — the risk of injury. We feel for him.”

On the play that led to the injury, Hayward was leaping toward the basket to receive a pass from Irving when he became entangled with LeBron James and Jae Crowder of the Cleveland Cavaliers. Hayward landed on his left foot, which twisted in gruesome fashion under him as he collapsed to the floor.

The reaction to the injury was immediate, with Tristan Thompson of the Cavaliers covering his face and turning away. Players from both teams were visibly shaken as medical personnel rushed to tend to Hayward, 27, whose left leg was eventually placed in a protective brace. Several players, including James, approached Hayward to wish him well as he was placed on a stretcher and wheeled off the floor. The crowd at Quicken Loans Arena, which had been silent following the play, gave him an ovation.

“It was hard to see,” Horford said, adding: “We need to regroup.”

Shortly after Hayward was taken off the court, the Celtics announced that he had received a diagnosis of a fractured ankle. After the game, Stevens, who also coached Hayward in college at Butler, clarified that the injury was a dislocated ankle and a fractured tibia, and that Hayward was being transported to Boston for more treatment.

The Celtics, minus their new star, went on to lose to the Cavaliers, 102-99.

Boston drastically revamped its roster in the off-season despite having been the top seed in the Eastern Conference in last season’s playoffs. Hayward was brought in as a free agent after seven years with the Utah Jazz, and Irving was added in a trade with the Cavaliers. The Celtics jettisoned franchise mainstays like Isaiah Thomas, Crowder and Avery Bradley.

Thomas, who had helped recruit Hayward to Boston before he was sent to Cleveland in the trade for Irving, was reported to have visited Hayward in Cleveland’s locker room while he was being evaluated by members of the medical staff from both teams. James was also reported to have visited Hayward.

Without Hayward, the Celtics fell behind by as many as 18 points, but they rallied and took a lead with less than two minutes left in the game. Down the stretch, Boston could not keep up and the Cavaliers closed the game on a 7-1 run to secure the 3-point victory. James finished the game with 29 points, 16 rebounds and 9 assists while Irving, his former teammate, had 22 points and 10 assists but missed a last-second 3-pointer that would have tied the game.

Hayward’s injury, which was reminiscent of a compound fracture that Paul George of Oklahoma City sustained during an Olympic exhibition three years ago, rendered the result of a much-anticipated game almost meaningless. The Celtics did not provide an immediate timetable for Hayward’s rehabilitation, but it figures to be a lengthy process.

Athletes and coaches from across the N.B.A. and other sports leagues reacted with horror and sympathy immediately after the injury was broadcast on television.

Asked about it before his team’s opening-night matchup against the Houston Rockets, Coach Steve Kerr of the Golden State Warriors said, “It was terrifying. The whole coaches’ office was just devastated watching it. It just shows the fragile nature of what we do.”

The outpouring of well wishes on Twitter was also swift.