Tyronn Lue is stepping away from his role as the Cleveland Cavaliers' head coach due to health reasons, the team announced on Monday.
Associate head coach Larry Drew will take over with Lue suffering from chest pains and a lack of sleep, among other ailments.
Neither the Cavs nor Lue put a timeframe on the 40-year-old's recovery.
Lue, who took the reins in 2016, has missed parts or all of three games because of the issues, including the second half of the Cavs' 114-109 win over the Chicago Bulls on Saturday.
"After many conversations with our doctors and Koby [Altman, GM] and much thought given to what is best for the team and my health, I need to step back from coaching for the time being and focus on trying to establish a stronger and healthier foundation from which to coach for the rest of the season," Lue said in a release.
"I have had chest pains and other troubling symptoms, compounded by a loss of sleep, throughout the year. Despite a battery of tests, there have been no conclusions as to what the exact issue is.
"While I have tried to work through it, the last thing I want is for it to affect the team. I am going to use this time to focus on a prescribed routine and medication, which has previously been difficult to start in the midst of a season.
"My goal is to come out of it a stronger and healthier version of myself so I can continue to lead this team to the championship we are all working towards."
"We know how difficult these circumstances are for coach Lue and we support him totally in this focused approach to addressing his health issues," added Altman.
LeBron James told reporters after the win over the Bulls that Lue's health problems were affecting the Cavs, who are 40-29 and sit third in the Eastern Conference, only half a game ahead of the Washington Wizards and the Indiana Pacers.
"I mean he's the captain of the ship, so absolutely," James said. "We worry about his health, obviously. That's way more important than this game of basketball. We know he's been doing everything he needs to do to stay healthy - [maybe he should] take even more measures to get himself right.
"Everything that's been going on with our year, it's just another one."
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