The basketball world is mourning the death of Don Nelson, one of the most influential coaches in NBA history.

Nelson died Sunday at the age of 86, according to reports and statements from NBA organizations.

His coaching career was defined by innovation.

Nelson became famous for his unconventional approach to basketball, including the style that became known as “Nellie Ball.” His teams frequently challenged traditional ideas about positions, pace and offensive structure.

He also finished his coaching career with the second-most regular-season wins in NBA history.

A career that changed basketball

Before becoming a coach, Nelson was also an outstanding player.

He won five NBA championships as a player with the Boston Celtics, giving him an extraordinary connection to the history of the league.

His influence continued long after his retirement.

Many modern NBA concepts emphasize positionless basketball, spacing and versatile players. Nelson was experimenting with versions of those ideas decades earlier.

Tributes from around basketball

Teams, former players and coaches have expressed their condolences following his death.

For many basketball fans, Nelson represented an important bridge between older generations of the NBA and the modern game.

His legacy will not simply be measured by wins.

It will also be remembered through the ideas he introduced to basketball.