Boston Celtics forward Gordon Hayward suffered a horrific ankle injury just six minutes into his debut with the team as they lost 102-99 to the Cleveland Cavaliers.

Hayward had been attempting to finish off an alley-oop pass from Kyrie Irving when he collided with LeBron James and Jae Crowder on the way up before landing awkwardly.

Players looked visibly shaken as Hayward lay on the court in agony with a clearly twisted left ankle.

The Celtics later confirmed that the 27-year-old had suffered a fractured ankle – a heavy blow for the team, who had hoped their star recruit would help to close the gap on the Cavaliers in the Eastern Conference.

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.