Australian Open 2017: The return of Roger Federer and Rafa Nadal

Updated 1735 GMT (0135 HKT) January 24, 2017

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Prior to the Australian Open, Roger Federer had dropped out of the world's top 10 rankings because of a six-month absence from the Tour with a knee injury.
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But the 17-time grand slam champion has returned to form in Melbourne Park, going further in the tournament than top seed Andy Murray and defending champion Novak Djokovic. PETER PARKS/AFP/AFP/Getty Images

Federer's opponent in the quarterfinals was the unseeded Mischa Zverev, the world No. 50 who had surprisingly knocked out favorite Murray in the fourth round. WILLIAM WEST/AFP/AFP/Getty Images

The 35-year-old Federer surprised himself -- but perhaps not his devoted fans -- as he destroyed the German in straight sets in just 92 minutes to reach his 13th Australian Open semifinal. PAUL CROCK/AFP/AFP/Getty Images

The Swiss' joy at progressing was evident as he became the oldest player to reach a grand slam semi-final since a 39-year-old Jimmy Connors did so at the US Open in 1991. Michael Dodge/Getty Images AsiaPac/Getty Images

Federer, ranked world No. 17, could play old adversary Rafael Nadal in the final Sunday, a player he has only beaten in 11 of their 34 previous meetings. Cameron Spencer/Getty Images AsiaPac/Getty Images

But first Federer must overcome compatriot and three-time grand slam champion Stan Wawrinka in the semifinals for a shot at winning a fifth Australian Open title. SAEED KHAN/AFP/AFP/Getty Images