Don Nelson, a five-time NBA champion with the Boston Celtics and one of the winningest coaches in league history, died Sunday at the age of 86, his family announced in a statement. A cause of death was not shared.“On Sunday morning our beloved husband, dad, grandfather and great-grandfather Don Nelson peacefully went to be with the Lord, surrounded by his loving family,” the statement read. “Throughout his last week, friends and family encircled him with love, sharing the blessing of his friendship and revisiting treasured memories.”The pioneer of “Nellie Ball,” Nelson, who began his coaching career as an assistant in 1976 with the Milwaukee Bucks, is credited with using fast-paced offense and smaller, more athletic players to seek mismatches and outrun opponents on the court, which is an approach many teams adopt today. His success led to his being named to the NBA’s list of the Top 10 (1996) and Top 15 (2021) coaches of all time.On April 7, 2010, with his 1,333rd victory on the sidelines, Nelson passed Lenny Wilkens to set the NBA record for most regular-season coaching wins before finishing his career with a record of 1,335-1,063 (.556 win percentage). Nelson was inducted into the Naismith Basketball Hall of Fame as a coach in 2012. His 1,335 career regular-season wins trail only Gregg Popovich (1,390) for the league record.Although Nelson did not win any titles as a head coach, he experienced championship glory in his 14-season NBA playing career, helping the Celtics hang five banners over an 11-year stint. Nelson averaged 11.1 points on 50 percent shooting and 4.8 rebounds in 134 career playoff games for the Celtics. He’s among 26 players to win at least five NBA championships — 11 of those players did so with Boston — and Nelson’s No. 19 jersey was retired by the franchise in 1978.The Basketball 100The story of the greatest players in NBA history. In 100 riveting profiles, top basketball writers justify their selections and uncover the history of the NBA in the process.The story of the greatest players in NBA history.BuyBy 1965, the Celtics signed Nelson as a free agent, and his game and role grew in Boston. During his first season under new coach Red Auerbach, Nelson posted averages of 10.2 points and 5.4 rebounds to help the Celtics win the 1965-66 championship. He contributed as a sixth man for a roster that included Boston legends Bill Russell, Sam Jones, John Havlicek, Satch Sanders and KC Jones. During the 1967-68 season, he was one of seven Celtics to average double-figure points, which at the time tied an NBA single-season record. The 2023-24 Hawks (eight) are the only team to have more such players. In nine seasons as a Celtic, Nelson averaged at least 10 points nine times.In Game 7 of the 1969 NBA Finals, Nelson had perhaps the most memorable moments of his storied basketball career. With just over a minute left in the matchup, he made a foul-line jumper that initially hit the back rim and bounced multiple feet into the air before falling to give Boston a 103-102 lead en route to a 108-106 win over the rival Los Angeles Lakers. The shot helped notch the Celtics’ 11th championship in 13 seasons as Russell’s legendary career, which included two final seasons as player-coach, drew to a close.