Boston's Gordon Hayward suffered a gruesome broken left ankle injury barely five minutes into the new NBA season Tuesday, overshadowing the Cleveland Cavaliers' 102-99 victory in Kyrie Irving's homecoming.

Hayward, the former Utah star who signed a four-year deal with the Celtics worth $128 million in the off-season, was stretchered off the court following a horrific injury that stunned players on both clubs.

Hayward landed hard 5:15 into the game after a leaping cut to the basket trying to catch an alley-oop pass from Irving, the ex-Cavaliers point guard who asked in the off-season to be traded and was sent to Boston.

Cleveland superstar LeBron James tried to break up the play. Hayward, 27, was caught in the air and when he landed, his left leg twisted unnaturally, his ankle turned at a grotesque angle.

Boston teammates huddled, clearly shocked at the mishap, and the Cavaliers were taken aback as well, their home arena falling silent as doctors began examining Hayward.

A standing ovation followed when Hayward was stretchered off with his left leg immobilized from foot to thigh, sitting up on the stretcher as he was carried off.

After he was examined by medical staff of both teams, the Celtics said he had been diagnosed with a broken ankle and would be flown back to Boston after the game.

"You hurt for him," Celtics coach Brad Stevens said. "He's put in a lot of great work and I thought he had his most comfortable week as far as feeling like he was going to play really well. "Now, hopefully we get a full recovery and it's a tough deal, but I guess that's part of it, the risk of injury."

Rookie Jayson Tatum added: "We prayed. We prayed for him, for his health, and we just told each other we have to keep pushing."

The injury cast a pall on the much-anticipated start to the NBA's 72nd season.

The pre-game spotlight focused on Irving and his return to Cleveland after being sent to Boston for Celtics point guard Isaiah Thomas and forward Jae Crowder, joining Cleveland's other new faces, former NBA Most Valuable Players Derrick Rose and Dwyane Wade.

- 'Something drastic' -

"It's not a great sight to see," Irving said, while Rose called it a "weird feeling".

"You know something drastic just happened like that," Rose said. "We've still got to go out there and play."

Irving, who teamed with james to reach three straight NBA Finals with the Cavs, winning the title in 2016, received a chilly reception from Cavs fans, who booed his introduction and every touch of the ball in the early going.

That included when he lofted a shot over James for the season's first basket.

"Any time you win a championship with someone, you automatically think about the moments and the memories, especially with someone who was instrumental to what we were able to accomplish," James said. "But once the ball went up, it was kind of back to our regularly scheduled program."

The Cavaliers led 54-38 at half-time and stretched the lead to 61-43 just 2:03 into the third quarter on a Kevin Love free throw.

But the Celtics battled back to take a 71-69 lead before the Cavs regained a slim 72-71 edge going into the fourth quarter.

Boston were up 98-95 before Love sank two free throws, James followed with a layup and then assisted on a 3-pointer by Love that gave the Cavaliers a 102-98 lead.

Irving made a free throw to pull Boston within the final margin, but Irving drove to the hoop against Rose and missed a shot that James rebounded.

A final Cleveland miss gave Boston one last chance to equalize. Irving missed a three-pointer at the buzzer, then got a hug from James.

Source: AFP