Donnie Nelson has been his father's assistant for nine years, including the past two in Dallas. He also is the team's director of player personnel.
He's never been an NBA head coach other than replacing his father following ejections and illnesses. He's coached summer leagues and Lithuania's Olympic team, which won the bronze medal in Sydney after nearly upsetting the United States in a semifinal.
The elder Nelson will leave the team following a home game against Detroit next Wednesday for an operation in Salt Lake City. Donnie's debut will come during a five-game road trip that begins Jan. 5 at Toronto.
"For this month and a half, I probably am the best Nellie replacement," the younger Nelson said.
Harris, who has coached more than 1,000 NBA games for Milwaukee, Houston and the Los Angeles Lakers, decided over the Christmas break that he wasn't right for the job.
The Mavericks, who are off to their best start in 12 years and trying to make the playoffs for the first time since 1990, went 1-3 for Harris when Nelson took time off to seek treatment options.
"It's a great system, but I found it to be a system different from the way my instincts are," said Harris, who was hired as a defensive specialist and will remain with the team. "I think I make a good helper in the system. In this situation, I thought it better for the team to keep doing it the way we're doing it here."
Donnie came to Dallas after 2 1/2 seasons as an assistant at Phoenix. At the time, there was talk of him eventually replacing his father, who also is the Mavericks' general manager, as coach. Those plans were scuttled after Mark Cuban bought the team in January.
Cuban approved this change, which could be for 17 to 23 games.
©2000 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed