- Federer and Nadal have won a combined 37 majors, including the last six
- Federer, 36, is the favorite to defend his Wimbledon title
- 1987 Wimbledon champion Cash talked exclusively to CNN Sport
Federer will be bidding to extend his record to nine Wimbledon crowns when the tournament begins next week, a little over a month shy of his 37th birthday.
Nadal won a record-extending 11th French Open title last month, shortly after turning 32.
Australia's Pat Cash, who won Wimbledon at the age of 22 in 1987 for his sole major title, told CNN Sport at Roland Garros he is amazed by their "freakish" motivation bordering on "obsession."
"I don't understand how he [Nadal] does it, I really don't know. It's some form of obsession, there is no doubt about it, I don't know what drives him, but it has to be," said Cash, who now coaches American Coco Vandeweghe.
"Federer as wel