Nadal moves on in Melbourne

Melbourne, Australia ( - Top seed Rafael Nadal earned a hard-fought victory during Monday's fourth round to secure a spot in the quarterfinals at the Australian Open.

Nadal, who missed last year's Aussie Open due to a knee injury, was tested mightily by Japan's Kei Nishikori, but the top-seeded Spaniard staved off the 16th-seeded Nishikori to claim a 7-6 (7-3), 7-5, 7-6 (7-3) triumph on Rod Laver Arena.

Nadal, the 2009 titlist and 2012 runner-up at Melbourne Park, will next face Bulgarian Grigor Dimitrov, the No. 22 seed, after he secured a spot in the quarterfinals with a 6-3, 3-6, 6-2, 6-4 win over Spaniard Roberto Bautista Agut.

The 22-year-old Dimitrov will be making his first appearance in a Grand Slam quarterfinal, while Nadal will be appearing in his seventh quarterfinal at the Australian Open alone.

Fourth-seeded Andy Murray and lucky loser Stephane Robert of France are still in action on Hisense Arena, with Murray leading two sets to one heading into the fourth set.

Sixth-seeded Roger Federer and 10th-seeded Jo-Wilfried Tsonga will take the court during Monday's evening session, with the winner to take on the victor between Murray and Robert in the quarterfinals.