Cleveland Cavaliers coach Tyronn Lue is stepping away from coaching to focus on his health, the team said Monday.
Lue told ESPN's Rachel Nichols via text message that his goal is to return in about a week.
Lue, 40, left Saturday night's 114-109 victory against the Chicago Bulls with an illness, marking the third time this season that his health has kept him from coaching an entire game.
"After many conversations with our doctors and [general manager] Koby [Altman] 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 statement.
"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."
Lue has also been coughing up blood, team sources told ESPN's Dave McMenamin.
Associate head coach Larry Drew will take over in the interim.
"[Lue] texted me about 1:30 this morning and just told me, 'It's your show,'" Drew said Monday. "He wants me to go out there and just kind of do what I do.
"We'll tweak some things, we'll add some things, but for the most part we'll do what we've been doing. I don't want to confuse the guys."
Lue pushed to return to Saturday's game, league sources told ESPN's Adrian Wojnarowski, only to be persuaded by staff to stay in the locker room and let Drew finish the game.
The team "shut him down," one source familiar with what happened told McMenamin. "The only way it was going to happen was if they did it," the source said. "He never wanted to be perceived as letting his team down. They took the decision out of his hands."
Lue is hoping to reset his health with a new personal chef, regular exercise, rest and medication.
"While I have tried to work through it, the last thing I want is for it to affect the team," Lue said in the statement. "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."
Said Altman: "We know how difficult these circumstances are for Coach Lue and we support him totally in this focused approach to addressing his health issues."
"It's probably well overdue," forward LeBron James told reporters Monday. "He's been going through a lot this season."
"I think players understand that coaches go through [medical issues] just like players do," Drew said Monday. "What T. Lue has shown is shown the warrior that he is. If you would have left it up to him he'd be sitting in this chair right now instead of me, that's just who he is.
"He wants to be with the team, but there comes a point where you have to take a step back and you really have to assess things ... this thing has kind of been lingering just a little bit too long. He needs to really just step away and allow himself to heal before rejoining the team."
Lue had to leave a loss to the Orlando Magic on Feb. 6 because he was not feeling well. He also missed a game Dec. 21 against the Bulls with an undisclosed illness, needing to stay in the locker room after arriving at the arena and going through his pregame media duties.
Lue was shaken when Charlotte Hornets coach Steve Clifford missed 21 games earlier this season because of headaches caused by sleep deprivation. At the time, Clifford said doctors told him he needed to change his lifestyle and work habits dramatically.
Clifford reached out to Lue on Monday but hadn't yet connected with him, Clifford told ESPN.
Clifford coached Lue as part of staffs in Orlando and Houston and has enjoyed a strong relationship with him.
"I feel for Ty," said Warriors coach Steve Kerr. "We've been in contact and we -- health is everything. This game is fun, and it's exciting, and we all love our jobs. But we just want to be healthy. We just want everyone to be healthy: the players, the coaches. So we're thinking about Ty and hoping he can recover quickly and find some answers and get back on the sidelines because he's a great guy. He's a great representative for their team and for the league."
When asked what might contribute to health-related issues for NBA coaches, Kerr said, "I think sleep is a big deal.
"There's a lot of recovery that goes on when you're resting, and you need that. You need to eat well; you need to stay hydrated. But things happen. That's what I've learned. Stuff happens, unexpected stuff. And you've got to just deal with it and do the best you can."
Lue considered stepping away earlier in the season due to his health issues, but he resisted during the team's early-season free fall because he didn't want to give the appearance that he was leaving the team during a losing streak. He resisted stepping away again after February's trade deadline roster overhaul because he wanted to help integrate the new players into Cleveland's lineup, league sources told Wojnarowski.
"Now you guys understand what coaches have to go through," Knicks coach Jeff Hornacek said. "It's hard. ... It's tough. It's a stressful job. And it's hard because all the coaches work extremely long hours. There's always a game to watch, always another film to watch. You want to be as best prepared as you can and sometimes you fail to realize what your health is doing with lack of sleep and stuff like that."
ESPN's Michael C. Wright, Nick Friedell, Ian Begley and The Associated Press contributed to this report.