Paul Flory, chairman of the Western & Southern Open tennis tournament in Cincinnati, has died from complications relating to Alzheimer's disease.

The 90-year-old took over as the tournament's director in 1975 and built it into one of the ATP Tour's five Masters 1000 events, alongside Rome, Madrid, Indian Wells and Miami.

Leading the tributes was ATP CEO Brad Drewett, who said: "Paul is a dear friend of the ATP and we will always be grateful for the contributions he made to the ATP and tennis."

Roger Federer's coach Paul Annacone also expressed his respects on Twitter, posting: "Paul Flory, a true gentlemen and a genuine leader in the tennis industry-thank you - you will be missed."

Andy Murray's former coach Brad Gilbert posted: "Paul Flory, one of the great contributors to tennis, Hands down put Cincinnati on the map. Tennis has lost a true and genuine giant."

This year's W&S Open begins on August 11.