The 2017-18 NBA season didn’t get started quite the way the Boston Celtics had hoped.

Facing off against the Eastern Conference-rival Cleveland Cavaliers, the Celtics debuted their two new star players: Gordon Hayward and Kyrie Irving.

Irving had all the attention before the game since he was returning to Cleveland, in which he spent the first six years of his NBA career. By halftime, though, all eyes in Quicken Loans Arena were focused on Hayward.

Just five minutes into his first game with the Celtics, Hayward went down with a gruesome injury, colliding with LeBron James while going up for an alley-oop. Hayward’s leg twisted when it hit the ground, causing the scary scene.

The Celtics announced after the game that Hayward dislocated his left ankle and fractured his left tibia.

Here’s a look at the play. Warning: It’s tough to watch:

The Cavaliers bench reaction summed up how bad the injury was for Hayward:

The Cavaliers won the game, 102-99, to open the NBA season. Hayward previously signed a four-year, $128 million free-agent contract with the Celtics this summer. There’s no official timetable for his return, but Hayward likely will miss the rest of the regular season for Boston.

"At the end of the day, there's still a game to be played. As s---ty as that sounds, but still a game to be played," Irving said after the game to ESPN. "We understand that; we're professionals. When one of our brothers goes down, we just pick the rest of our guys up and understand that we send our well-wishes to him and his family, and we'll see him on the plane. We'll do what's needed for him to get through the process of getting back healthy."

UPDATE: Hayward is getting closer to full health. Take a look at him shooting some 3's on the court:

 

Still can’t beat me... 🤷🏻‍♀️

A post shared by Robyn Hayward (@robynmhayward) on

Maybe he'll back sooner than everyone thinks.