Novak Djokovic cruises into last 16 at Australian Open

Djokovic is through to the Australian Open last 16 for the sixth successive year

Defending champion Novak Djokovic beat France's Nicolas Mahut 6-0 6-1 6-1 in 74 minutes to ease into the Australian Open fourth round in Melbourne.

Mahut was hampered by a knee injury and never looked like threatening the Serbian's bid for a third title.

Djokovic plays Lleyton Hewitt in the last 16 after the Australian beat 23rd seed Milos Raonic in four sets.

Sixth seed Jo-Wilfried Tsonga of France overwhelmed Portugal's Frederico Gil with a 6-2 6-2 6-2 win.

Djokovic's victory last year was the first of three Grand Slam titles in an outstanding 2011 and the world number one has yet to drop a set in three matches in Melbourne in 2012.

Tsonga's win was his eighth successive victory

Despite his injury and several on-court discussions with the trainer, Mahut showed the gritty determination that marked his 2010 Wimbledon epic against John Isner to complete the match.

"Credit to him, we saw some taping around his knee and I felt sorry for him," said Djokovic.

"Evidently he was not playing his best or moving too well but he did not want to retire from the match."

Tsonga's victory keeps him on track for a potential last-eight meeting with British number one Andy Murray.

The Frenchman's combination of power and athleticism on the Hisense Arena overwhelmed Gil who had been the first man from his country to make a Grand Slam third round.

After Tsonga had breezed through the opening two sets, Gil forced break points in the second and fourth games of the third set as the 2008 finalist took his foot off the pedal.

But Gil, ranked 107 in the world, could not take the chance to increase the pressure towards the finish.

Kei Nishikori stands between Tsonga and the quarter-finals as he became the first Japanese man into the Australian Open fourth round in the Open era with a 4-6 7-6 (7-3) 7-6 (7-4) 6-3 win over Julien Benneteau.

Kazakhstan's Mikhail Kukushkin produced the shock of the day as he made up 77 ranking places on world number 15 Gael Monfils to dump the Frenchman out 6-2 7-5 5-7 1-6 6-4 in an occasionally bad-tempered match on the Margaret Court Arena.

Monfils was restricted by a back injury, but threatened to deny Kukushkin his first apperance in the fourth round of a Grand Slam before his 24-year-old opponent composed himself to set up a meeting with Murray.

Fifth seed David Ferrer was broken in his first two service games against Argentina's Juan Ignacio Chela, but recovered strongly to win 7-5 6-2 6-1.

Ferrer, a semi-finalist last year, will play France's Richard Gasquet for a place in the last eight after the 17th seed upset Janko Tipsarevic in straight sets.

The 6-3 6-3 6-1 defeat marked the eighth successive Australian Open campaign to have ended before the fourth round for world number nine Tipsarevic.