Men's tennis boss Brad Drewett said he was stepping down after being diagnosed with motor neurone disease, in a sudden announcement that prompted a wave of tributes and sympathy. The 54-year-old Australian said he will continue as executive chairman and president of the Association of Tennis Professionals (ATP) until a replacement is appointed. "It has been a privilege to serve as executive chairman and president of the ATP, an organisation that I've been a part of for more than 35 years since I became a professional tennis player," Drewett said in a statement. "I hold the ATP very close to my heart and it's with sadness that I make the decision to enter this transition period due to my ill health." The news, on day two of the Australian Open, prompted expressions of sympathy from well-wishers including Roger Federer, who called it "very sad news". "Brad has become a good friend of mine over the years and this is very sad news for all of us at the ATP and the entire tennis community," the world number two said in the ATP statement. "He is well liked and respected by everyone and has done a tremendous job in leading the ATP over the past 12 months, overseeing some major initiatives and a record-breaking year in 2012. "His dedication and service to the sport over the years has been truly admirable and he has been a central figure in helping to grow the ATP product across the globe. "Our thoughts are with him and his family during this difficult time." Tributes were also paid by Tennis Australia and the Grand Slam Committee, which governs the sport's four major tournaments. "Brad's long-standing commitment to the sport marks him as a true member of our tennis family and we wish him well in the fight ahead," the committee said in a statement. Drewett won two singles titles in the early 1980s during his playing career. Since becoming ATP chief last year, he was instrumental in gaining increased prize-money for players. Motor neurone disease, also known as Lou Gehrig's disease, is incurable. The life expectancy after diagnosis is normally three to five years. From AFP