Nick Bollettieri, who coached many of tennis’ greatest athletes, died Sunday at his home in Bradenton, Florida, at the age of 91. Bollettieri, who was inducted into the International Tennis Hall of Fame in 2014 despite never having played the game professionally, produced an astounding 10 international No. 1 players by the end of his career, from Andre Agassi to the Williams sisters. Nicholas James Bollettieri was born in Pelham, New York, on July 31, 1931 to a pair of Italian immigrants. Having barely touched a racket before, he began coaching the sport to support himself through law school, reportedly knowing so little about the sport that he would convene with local tennis pros before each lesson for advice, according to the Pittsburgh Post-Gazette. Bollettieri’s legacy would be cemented decades later in 1978 when he pioneered the idea of a tennis boarding academy, which would become the Nick Bollettieri Tennis Academy and later evolve into IMG Academy, with a curriculum so rigorous under his helm that it drew comparisons to a factory and correctional camp. “Our dear friend, Nick Bollettieri, graduated from us last night,” said Agassi. “He gave so many a chance to live their dream.”