6: Roger Federer
A legend who is still gracing his sport, Federer has reached the point now where people already consider him to be the best his sport has ever seen... and he hasn't even finished yet!
The Swiss maestro holds a remarkable 17 Grand Slams to his name as well as having being ranked world No.1 for the longest period at any one time (302 weeks).
The 32-year-old still has a little left in the tank, but it doesn't matter what he does now- he's already done virtually everything there is to do.
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