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While much of the basketball world was focused on the NCAA tournament action, the NBA's Los Angeles Lakers suffered a serious setback Saturday, losing superstar LeBron James to injury.

James left in the second quarter with what was called a high right ankle sprain. The Lakers said the injury will sideline James indefinitely.

The Lakers went on to fall 99-94 to the Atlanta Hawks at the Staples Center in Los Angeles.

The 36-year-old James later expressed his disappointment in a Twitter message -- but vowed to get back to the court.

"Nothing angers and saddens me more than not being available to and for my teammates!" James wrote. "I’m hurt inside and out right now. The road back from recovery begins now. Back soon like I never left."

ESPN's Dave McMenamin later posted on Twitter that James was able to accompany his Lakers teammates on a flight to Phoenix for their next game against the Suns.

The defending NBA champions already are without All-NBA big man Anthony Davis, who has missed 14 consecutive games with a right calf injury and likely won't play again until April.

Los Angeles Lakers forward LeBron James holds his ankle after going down with an injury during the first half of an NBA basketball game against the Atlanta Hawks, March 20, 2021, in Los Angeles. (Associated Press)

Los Angeles Lakers forward LeBron James holds his ankle after going down with an injury during the first half of an NBA basketball game against the Atlanta Hawks, March 20, 2021, in Los Angeles. (Associated Press)

James was hurt when he rolled his ankle under Solomon Hill, who was called for a foul as he reached awkwardly for a steal. The Lakers star screamed and fell to the court clutching at his ankle, yet he got up and briefly stayed in the game.

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"I haven’t necessarily seen him scream and squall like that, probably ever, not even with that groin," said Kyle Kuzma, who was with the Lakers when James missed 17 games with a groin injury two seasons ago. "It had to hurt a little bit, for sure."

After the injury, James hit a corner 3-pointer that extended his NBA-record streak of games with at least 10 points to 1,036, but he called a timeout and left the court shortly afterward. James knocked over a chair in frustration as he went to the locker room.

"The mood of the team is we’re disappointed we lost, and we’ve got to come back and get one tomorrow," Lakers coach Frank Vogel said. "I won’t disclose what LeBron was like (in the locker room). It’s in-house."

John Collins had 27 points and a season-high 16 rebounds, and Trae Young added 14 points and 11 assists for the Hawks. They opened an eight-game trip with their eighth straight victory under new coach Nate McMillan — but only after their defending champion opponents lost their 17-time All-Star to an injury that could shake the NBA’s balance of power if it turns out to be serious.

James’ absence left the Lakers without three starters in the second half, and the Hawks capitalized for their first road victory over Los Angeles since March 2016. Along with Davis, Marc Gasol missed his seventh straight game since February after sitting out under the NBA’s health and safety protocols.

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"It’s different without (James), without AD," Gallinari said. "Of course they’re a different team. But at the same time, all of the players that stepped up are all NBA veterans with experience, guys that won championships. I would say it’s anyway a very good win."

Montrezl Harrell had 23 points and 11 rebounds, while Dennis Schröder had 16 points and seven assists against his former team for the Lakers, whose four-game winning streak ended amid much bigger concerns.

Harrell suggested Hill's actions during James' injury were "not a basketball play," and said the officials should have considered giving him more than a personal foul.

The Associated Press contributed to this story.