Roger Federer can't contain his joy after vanquishing Japan's Kei Nishikori in five sets on Sunday night to reach the quarterfinals of the Australian Open. [Photo/Agencies]

Swiss superstar defies long odds to become favorite

It seemed unthinkable just a few days ago, but Roger Federer's chances of winning an age-defying 18th Grand Slam title look better all the time after an astonishing turn of events at the Australian Open.

After top-ranked Andy Murray followed defending champion Novak Djokovic with an early exit, 35-year-old Federer gritted his teeth to reach the quarterfinals - and has been installed as the betting favorite.

There was no doubt what it meant to Federer, who leapt around in celebration after completing a hard-fought 6-7 (4), 6-4, 6-1, 4-6, 6-3 win over Japan's Kei Nishikori late on Sunday.

"This is a huge moment for me in my career," said the grinning Swiss, who could write a new chapter following his return from a six-month layoff while he recovered from a knee injury.

Federer hasn't won a Grand Slam in five years, and he could also become the oldest player since 37-year-old Ken Rosewall in 1972 to win one of the sport's major trophies.

Playing with his old panache, he remains a huge favorite of the Australian crowds who have seen him victorious on four occasions at Melbourne Park.

But with a lot of tennis to be played over the next week, it's still too early to talk of a record-extending 18th major for Federer, starting with his quarterfinal against Mischa Zverev.

A victory on Tuesday would put him into a semifinal against his fellow Swiss, the redoubtable Stan Wawrinka, or France's Jo-Wilfried Tsonga.

On the other side of the draw lurk third seed Milos Raonic of Canada and Grigor 'Baby Fed' Dimitrov - and Federer's old nemesis, Rafael Nadal.