"The objective of this exhibition match is to set a spectator record for a game of tennis, exceeding 80,000," the nine-times European champions said on their website.
The charity event, to be played on July 14, is being organised by the Realmadrid Foundation and the Rafa Nadal Foundation, with the proceeds going to projects developed by both around the world.
Spaniard Nadal is a well-known Real fan while Serbian Djokovic has been a guest of honour at the club's facilities, and once wore a Real shirt when he walked out for a tennis match at the Madrid Masters.
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