Bobcats president of basketball operations Rod Higgins said in a release Friday that Clifford is "resting comfortably" in the hospital but it's too early to know when he'll return to work. Higgins says Clifford checked himself into the hospital Thursday night because he was suffering from chest pains.
Clifford, 52, joined the Bobcats this offseason after spending last year as an assistant coach with the Los Angeles Lakers.
The Bobcats are off to a 3-2 start under Clifford.
Hall of Famer Patrick Ewing will serve as Charlotte's acting head coach against the New York Knicks Friday night.
Clifford becomes the second professional coach to check himself into a Charlotte hospital in the last week. Denver Broncos coach John Fox, who used to coach the Panthers and still owns a home in Charlotte, was admitted last Saturday with chest pains after experiencing pain while on the golf course.
Rookie Cody Zeller said he didn't find out Clifford was in the hospital until he reported to shoot-around on Friday morning.
"I just texted him and said I was keeping him in my prayers but I don't know much past that," Zeller said.
Clifford joined the Bobcats on May 29, replacing Mike Dunlap, who was fired after the Bobcats went 21-61.
The Bobcats have been thrilled with Clifford's approach thus far, saying he has the right makeup to deal with professional players. He spent 13 seasons as an NBA assistant coach for the Knicks, Orlando Magic and Houston Rockets and Lakers.
Ewing, the team's associate head coach, addressed the media before the game and said he's "a little nervous" about coaching his first game, particularly on such short notice.
But he said his biggest concern right now is with Clifford.
"Coach Clifford and I have been friends for a lot of years—we've worked together for over 10 years now—and this is definitely not the way I wanted to start my head coaching career with him being in the hospital," Ewing said.
Ewing, a member of the Professional Basketball Hall of Fame, played 15 seasons for the Knicks from 1985-2000.
The former Knick said, "It's ironic that my first chance to be a head coach will be against a team I played with for 15 years."