MELBOURNE - Olympic and US Open champion Andy Murray has been seeded third for this month’s Australian Open tournament, the first Grand Slam of 2013.Defending champion and world number one Novak Djokovic has been seeded first for the men’s singles event, while Roger Federer - who defeated Murray in the final of Wimbledon last year - is second seed.Last year’s runner-up Rafael Nadal will miss the tournament due to injury, so fellow Spaniard David Ferrer will be seeded fourth with Tomas Berdych fifth and Olympic bronze medallist Juan Martin Del Potro sixth.For the women’s singles draw, 2012 Australian Open winner Victoria Azarenka is top seed for her title defence, ahead of second seed Maria Sharapova and Serena Williams in third.Agnieszka Radwanska is fourth seed, with Angelique Kerber fifth and Li Na sixth. The 2013 tournament gets underway in Melbourne on January 14.