World number five Roger Federer has admitted he is inspired by Lleyton Hewitt and the determination the Australian has shown in his career.
Federer still obtains the record of winning 17 single Grand Slam titles, with Pete Sampras in second place with 14.
However, the Swiss player is currently at his lowest world ranking in a decade and is acquiring inspiration from fellow tennis star Hewitt.
Federer said to Zurich's NZZ am Sonntag: "Lleyton Hewitt is a good example for me, the ranking could be 170th, 20th or 5th - it's fun just to play."
32-year-old Hewitt has carried on performing to a high standard despite having to undergo multiple foot surgeries, the Australian has even reached the quarter-finals in the BB&T Atlanta Open.
Hewitt has exhibited exceptional spirit to overcome his injuries and still performs at an elite level - Federer wants to take a leaf out of Hewitt's book.
He has also admitted that he has no qualms over any criticism or negative opinions he receives.
Federer, 31, said: "My motivation is at the top. If I got to the point where I'd had enough of the travel and training then I would ask serious questions. But that's not the case now.
"There comes a time when the ranking is not so important. Quite honestly, I don't even know exactly what my current ranking. 4th? 5th? 3rd? It doesn't matter to me so much.
"I have no problem with criticism, but I expect us to be honest.
"This situation is not new for me. In 2009 and 2010 already, people said: 'He's won everything, now it's finished.' The more people that comment, the more likely that someone will be talking nonsense."
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