Former NBA commissioner David Stern underwent emergency surgery after suffering a brain haemorrhage on Thursday.
According to reports, the 77-year-old was taken to hospital after collapsing at a New York restaurant.
An NBA statement read: "NBA Commissioner Emeritus David Stern suffered a sudden brain haemorrhage earlier today for which he underwent emergency surgery.
"Our thoughts and prayers are with David and his family."
Stern spent 30 years in charge of the league before relinquishing the commissioner role to Adam Silver in 2014.
NBA Hall of Famer and former Los Angeles Lakers president of basketball operations Magic Johnson was among the well-wishers who shared messages of support on social media.
"Join Cookie and I in praying for my good friend who helped save my life, former NBA Commissioner David Stern," he wrote on Twitter.
"He suffered a brain haemorrhage and had to have emergency surgery."
Lakers shooting guard Danny Green posted: "Biggest prayers out to David Stern and the Stern Family....sad sad news, but we know he's a fighter and will make it through!"