WASHINGTON, Jan. 3 (Xinhua) -- NBA champions Miami Heat coach Pat Riley has taken indefinite leave of absence due to persistent hip and knee problems.

    Assistant Ron Rothstein will assume head coaching duties on an interim basis while Riley receives treatment on his right knee and left hip, the team said on its Web site (www.miamiheat.com) on Wednesday.

    Riley, 60, who guided the Heat to the NBA championship in June, is scheduled to undergo knee surgery on Friday, and also likely to have a hip replacement soon after, according to the Sun-Sentinel newspaper.

    His absence is another setback for the Heat (13-17), who have played most of the season without injured All-Star Shaquille O'Neal.

    It's the second time Riley left the team in mid-season. He stepped down as coach in October 2003.

    Riley, who also led the Los Angeles Lakers to four titles, returned to the bench when Van Gundy resigned for personal reasons in December 2005.

    In 23 seasons as a coach with the Heat, Lakers and New York Knicks, Riley has compiled a regular-season record of 1,164-606 while going 171-107 in the post-season.