Melbourne, January 18:

Men’s tennis has moved swiftly from one dominant player to two, then the Big Three and now the Big Four, making this year’s Australian Open the least predictable in recent times.

World No 1 Rafael Nadal is seeded top, Novak Djokovic is defending champion but Britain’s Andy Murray is some bookies’ favourite, rankling three-time winner Roger Federer. Federer heads into the season’s opening Grand Slam without the top seeding for the first time since 2004 but encouraged by his US Open win in September. The Swiss is in search of his 14th Grand Slam title, which would equal the record set by Pete Sampras.

However, Federer has already lost twice this year to Murray, whose form is raising genuine hopes that he may be about to end Britain’s 73-year wait for a Grand Slam title. Murray has also smashed past Nadal and defended his Qatar Open title in a rip-roaring start to the year after dominating the latter part of last season.

Murray’s physical fragility may be a worry in the 128-man draw after a back problem flared during the Doha semi-finals. He was also a first-round loser last year to Jo-Wilfried Tsonga. Djokovic is breathing down Federer’s neck for the second ranking but also has made an unedifying start to the season. The Serb blamed a change of racquet after losing to Ernests Gulbis in Doha, and was then ousted in the Sydney International semi-finals by Finland’s Jarkko Nieminen.

Sixth-ranked Tsonga dazzled Melbourne with his run to the final last year, but his build-up has been hit by a back injury which forced him out of the Sydney International. Czech player Radek Stepanek is buoyed by his Brisbane International win over Spaniard Fernando Verdasco, while Marin Cilic was victorious in Chennai and former No 1 Lleyton Hewitt may be a dangerous floater on home soil.

Federer opens his campaign on Monday against Andreas Seppi while Djokovic is playing Andrea Stoppini. On Tuesday, Nadal faces Christophe Rochus and Murray plays Andrei Pavel.