Originally Posted by Mike Sams
It's not just Nadal's knees that must stay healthy. His body, his focus, his mind and his determination must be absolutely spot on for the next 4-5 years.
He must be able to play at his prime level past his 30s which historically has never been done in the history of this sport.
The question is, how many years does he have where his body can still handle the ferocious grinding 4-5 hour battles against younger players?
Every year, things get tougher and tougher both physically and mentally for players who get up in age.
Just about everything must go right for Nadal for many more years in order for him to threaten such a record.
Yes, it would be difficult. But imagine it's August and Nadal has just won 2 slams convincingly. Wouldn't you start wondering if he could actually run the course? I imagine Federer would start feeling uncomfortable if that were to happen.