Nick Bollettieri, a famous tennis coach who founded of IMG Academy, has died.

He was 91.

Bollettieri coached tennis stars Serena and Venus Williams, Andre Agassi and Monica Seles.

IMG Academy, located in Bradenton, Fla., was used by many Major League Soccer teams as a preseason training base for many years and was the home to the U.S. Under-17 residency program. That program helped give the likes of recently named National Soccer Hall of Famers Landon Donovan and DaMarcus Beasley a place to train for the U-17 World Cup.

“RIP Nick Bollettieri,” former indoor and outdoor standout Kai Haaskivi said on Facebook. “The man who mastered the academy training concept it tennis. From 1995 to 1999, I had the privilege to work at the Bollettieri / IMG Academies as the Director of soccer and truly enjoyed the weekly interactions with Nick. Absolutely nobody could sell and “hype” the game of tennis and the Bollettieri Academy, like Nick did. Extremely unique, entertaining and successful individual, who will be missed.”

Added Ferdinando de Matthaeis on his Facebook page: “RIP Nick Bollettieri, an inspiration a great motivator, simply a legend. You used to call me ‘ paesano’ and you were always proud of your Italian roots. Ciao Nick ❤️👍🇮🇹”

Bollettieri, who was born in Pelham, N.Y., founded the Nick Bollettieri Tennis Academy in 1977 – which is the IMG Academy – after borrowing $1 million from a friend to build a live-in tennis academy

“Anyone who knew Nick knows how much he loved developing the potential in young people, coaching tennis and this Academy,” Tim Pernetti, president of IMG Academy Bradenton – a division of IMG Academy – told CNN.