MIAMI -- Miami Heat coach Pat Riley will take an indefinite leave of absence because of ongoing hip and knee problems, and top assistant Ron Rothstein will fill his spot on an interim basis.

The 61-year-old Riley disclosed his plans Wednesday, two days before he'll undergo surgery to remove floating chips in his right knee. He was not with the team Wednesday when it hosted the Clippers.

"I'm just tired of the pain and the medication," said Riley, who said there is no timetable for when he would like to return.

But he insisted he plans to be back with the defending champions.

"I'm going to be displaced for a while, but not disconnected at all," Riley said.

Riley, who also is the Heat president, is in his 12th season with the organization and 10th year as its coach. He resigned as coach shortly before the 2003-04 season, then returned to the bench in December 2005.