Don Nelson, the second-winningest coach in NBA history who won five championships as a player with the Boston Celtics, died on Sunday. He was 86.

Nelson’s death was announced by the Golden State Warriors, one of the teams he coached.

Nelson is one of two coaches in NBA history to have at least 250 wins with three different franchises – Milwaukee , Dallas and Golden State – also serving as general manager for all three franchises. He was a three-time coach of the year and made the playoffs 18 times in 31 seasons. He went to the conference finals three times with the Bucks and once with the Mavericks, although he never won an NBA title as a coach.

Nelson introduced what is now known as the point forward, and his up-tempo style of offense created a buzz. He said the idea of shifting from the dominant big men of the 1970s to an offense focused on speed and the fast break came from his playing days under Celtics Hall of Fame coach Red Auerbach.

Nelson played 11 of his 14 seasons in Boston and was on five Celtics championship teams under four different coaches. He became an assistant coach in Milwaukee after retiring as a player, then took over after coach Larry Costello resigned 18 games into the 1976-77 season. Nelson coached the Bucks for 11 seasons starting in 1976 and won seven straight division titles.

His fast-paced offenses were probably best on display with Golden State in the “Run TMC” era featuring future Hall of Famers Tim Hardaway, Mitch Richmond and Chris Mullin. Nelson said he wanted them on the court at the same time.

Nelson spent 11 seasons over two stints with Golden State. The first one was punctuated by a rift with rookie star Chris Webber, who was traded away a month into his second season. Nelson, demoralized by the trade, missed nine games that season due to illness and resigned under pressure three months later in February 1995.

In between, Nelson was fired after less than one season in New York in 1995-96, then coached in Dallas for eight seasons, taking time off after being diagnosed with cancer.

Nelson’s son, Donnie, joined his father as an assistant coach with the Mavericks in 1998, later became general manager and remained with the organization until 2021. Together they persuaded 20-year-old German star Dirk Nowitzki to pass up European basketball and join the Mavericks. Don Nelson also developed Steve Nash into one of the NBA’s top point guards before Nash went on to win back-to-back MVPs with the Phoenix Suns in 2005 and 2006.

At Golden State, Nelson’s “We Believe” Warriors led by Baron Davis upset Nowitzki and the top-seeded Mavericks in the first round of the 2007 playoffs in one of the biggest shocks in NBA history. In his final season as a coach, Nelson mentored rookie Stephen Curry in 2009-10.

Nelson retired as the NBA’s career coaching wins leader with 1,335, just ahead of Lenny Wilkens’s 1,332. Nelson kept that top spot for nearly 12 years before close friend and now-retired San Antonio coach Gregg Popovich passed him in March 2022.