BOSTON — Celtics fans lined up to sign a banner urging Gordon Hayward to "come back stronger than ever." One player wrote his injured teammate's initials on his shoe. The crowd that bought tickets to see him make his Boston debut chanted his name.

A few miles away, Hayward was being wheeled into surgery to repair the ankle he mangled in the season opener.

Hayward's agent said the surgery Wednesday night "went really well."

Mark Bartelstein said Thursday that doctors "got everything sort of fixed and put back in the right place. So that's great. There's no doubt we'll get him back to be better than he was before.

"There's no doubt in my mind about that."

Celtics coach Brad Stevens said the situation is difficult for him personally, but Hayward will have lots of support.

"Having known him as long as I've known him, it's tough to see him go through this," said Stevens, who was also Hayward's college coach at Butler. "We'll make sure he knows that we've got our arms around him."

After signing a four-year, $128-million free agent contract to come to Boston from the Utah Jazz, his only professional team, Hayward's Celtics career was less than six minutes old when an awkward landing in Cleveland on Tuesday night left him with a broken left tibia and dislocated ankle.

Bartelstein didn't have details on a timeframe for Hayward's recovery.

"It will be awhile," Bartelstein said. "I think it's very unlikely he'll play this season. But we're not even thinking about a timeframe right now."

Players on both teams reacted in horror to Hayward's gruesomely bent leg. Stevens said he couldn't watch the replay. The Celtics, who trailed the Cavaliers by 16 at halftime, lost when Kyrie Irving missed the potential tying 3-pointer at the buzzer.

Unable to attend the home opener against Milwaukee a night later, Hayward recorded a video message from his hospital bed before heading into surgery, telling Boston fans: "It's hurting me that I can't be there."

In the 30-second message, which was also sent out by the team on Twitter, Hayward thanked the fans for all the messages of support.

"I'm going to be all right," Hayward said. "It's hurting me that I can't be there for the home opener. I want nothing more than to be with my teammates and walk out on that floor tonight. But I'll be supporting you guys from here, and wishing you the best of luck."

Boston fell to 0-2 when Giannis Antetokounmpo scored 16 of his 37 points in the fourth quarter, adding 13 rebounds to help the Milwaukee Bucks to a 108-100 victory. Irving scored 17 points for Boston on 7-for-25 shooting, and Jaylen Brown scored 18.

Stevens said it's going to take them a little more time to figure this all out.

"I'm hopeful that we can find the right combinations," he said. "We obviously didn't anticipate going maybe this far into the bench this early."

Hayward was expected to make a full recovery, but Stevens did not know if he would be able to return this season.

"It's definitely been tough," said rookie forward Jayson Tatum. "We're just keeping Gordon in our prayers, hoping everything is all right."

Hayward's acquisition was part of a near-complete roster overhaul for the team that finished first in the East last season before losing to the Cavaliers in the conference finals.

The team also traded fan favourite Isaiah Thomas to Cleveland for Irving and shipped out regular starters Avery Bradley and Jae Crowder. In all, just four players on the roster finished last season with the team.

"As you saw in the Cleveland game, they fought back," Bucks guard Matthew Dellavedova said. "They're not going to quit."

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AP Sports Writer Kyle Hightower contributed to this report.

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