Rafael Nadal and Roger Federer were the undisputed King of Clay and King of Grass respectively. But who would win on a hybrid court made up of half grass and half clay?

That was the idea from Argentinean creative entrepreneur and tennis fan Pablo del Campo, who wanted to stage the exhibition match which would be watched by millions.

As Rafael Nadal retires from professional tennis, Pablo tells Uma Doraiswamy how he made the iconic court possible in May 2007 in a bid to find out who would win the Battle of the Surfaces.

Eye-witness accounts brought to life by archive and testimony. Sporting Witness is for those fascinated by sporting history. We take you to the events that have shaped the sports world through the eyes of the people who were there. For nine minutes, you become a fan in the stands as we take you back in time to examine memorable victories and agonising defeats from all over the world. You’ll hear from people who have achieved sporting immortality, or those who were there as incredible sporting moments unfolded.

Recent episodes explore the forgotten football Women’s World Cup, the plasterer who fought a boxing legend, international football’s biggest ever beating and the man who swam the Amazon river. We look at the lives of some of the most famous F1 drivers, tennis players and athletes as well as people who’ve had ground-breaking impact in their chosen sporting field, including: the most decorated Paralympian, the woman who was the number 1 squash player in the world for nine years, and the first figure skater to wear a hijab. You can learn all about fascinating and surprising stories, such as the tennis player who escaped the Nazis, how a man finally beat a horse in a race, and how the FIFA computer game was created.

(Photo: Rafael Nadal and Roger Federe compete in the Battle of Surfaces. Credit: Bob Martin/Sports Illustrated via Getty Images)