Calling Roger Federer the best indoor tennis player in history, former Wimbledon champion Pat Cash said he believes Federer can regain the No. 1 ranking.

Federer currently is trailing No. 1 Novak Djokovic by 2,430 points in the race for No. 1. Cash may have been referring to the season-ending ATP Race to London, to which the winner claims the unofficial title as No. 1 at season's end, according to tennisworldusa.org.

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"The way he's playing, and I've said this for a while, if Roger Federer stays fit, anything's possible," said Cash, who peaked at No. 4 during his ATP playing days. "There are very few men players who have not won a grand slam but become No. 1. I think Marcelo Rios is one. ... Scratching my head to think of another one who became No. 1 without winning a grand slam that year."

But the 33-year-old Federer, who already owns the record with 17 Grand Slam titles and 302 weeks as the No. 1 player in the world, seems in position to add to both records.

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Federer can accumulate as many as 3,000 points the rest of the year, while Djokovic can accumulate 2,500. Djokovic would have to flame out spectacularly or withdraw from tournament for Federer to have a chance.

According to tennisworldusa.org, Federer has the chance to become the first male player ever to have been shutout in the four Grand Slam events that can finish the season as the No. 1 player in the world.

"It just goes to show how well he's done in the other events," Cash said. "Indoors he is one of, if not, the best indoor players I've ever seen in my life; he's just incredible. So there's an absolute chance he can become No1. It'll be exciting."

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