(CNN) -- Sixth seed Juan Martin del Potro suffered a shock third-round defeat at the Australian Open on Saturday losing in five sets to unseeded Frenchman Jeremy Chardy.
The former U.S. Open champion and quarter-finalist in Melbourne 12 months ago had dropped just 13 games in his opening two matches, but Chardy soon had the big Argentine on the back foot taking the opening two sets with ease.
The third was much closer, finally going del Potro's way in the tiebreak and when the Argentine took the fourth set, Chardy's chances of pulling off an upset looked to have gone.
But the 25-year-old Frenchman, who hit 78 winners during the match, rallied to take the fifth and close out an impressive 6-3 6-3 6-7 3-6 6-3 victory in three hours 45 minutes.
"If I wanted to win, I had to take my chances and go for it. I'm very happy when my form is like this against a good player like Juan Martin," Chardy, ranked 36th in the world, said.
There were few alarms for the other top seeds in the men's draw. World No.2 Roger Federer saw off home favorite Bernard Tomic in straight sets 6-4 7-6 6-1 to set up a fourth round clash with Milos Raonic.
The 13th seed from Canada also recorded a comfortable win (7-6 6-3 6-4) over 17th seed Philipp Kohlschreiber from Germany.
Andy Murray is also safely through to the fourth round after beating Lithuanian qualifier Ricardas Berankis 6-3 6-4 7-5.
The Briton will play Gilles Simon for a place in the quarter finals after the Frenchman prevailed in a close-fought five setter (6-4 6-4 4-6 1-6 8-6) against compatriot Gael Monfils. The match, which took nearly four-and-three-quarter hours, included an incredible 71-shot rally in the second set which lasted two minutes and nine seconds.
No.21 seed Andreas Seppi progresses to the last 16 in Melbourne for the first time after beating Croatian 12th seed Marin Cilic in five sets 6-7 6-3 2-6 6-4 6-2.
The 2008 finalist and seventh seed, Jo-Wilfried Tsonga demolished Slovakia's Blaz Kavcic 6-2 6-1 6-4 to set up a fourth round meeting with compatriot Richard Gasquet who also completed a straight-sets victory (6-3 7-6 6-0) over Ivan Dodig.
In the women's draw, Serena Williams remains on course for a sixth singles title in Melbourne.
The third seed made light work of Japan's Ayumi Morita 6-1 6-3 to set up a fourth round tie against 14th seed Maria Kirilenko from Russia who was also a straight sets winner (7-6 6-3) over Belgium's Yanina Wickmayer.
Defending champion and top seed Victoria Azarenka was made to work harder on Saturday.
The 23-year-old prevailed in three sets 6-4 4-6 6-2 over Jamie Hampton from the U.S. and will face Russia's Elena Vesnina in the fourth round after she beat 16th seed Roberta Vinci 4-6 7-6 6-4.
America's Sloane Stephens is through to the fourth round for the first time after beating Britain's Laura Robson in straight sets 7-5 6-3.
The 19-year-old from Florida will play Serbia's Bojana Jovanovski -- a 6-2 7-6 winner over Japan's Kimiko Date-Krumm on Saturday -- for a place in the quarter final.
Denmark's Caroline Wozniacki will face Svetlana Kuznetsova of Russia in the last 16 after both women won their third round matches on Saturday.
Wozniacki, seeded 10th, beat Ukraine's Lesia Tsurenko 6-4 6-3 while Kuznetsova overcame Spain's Carla Suarez Navarro in three sets 6-2 4-6 6-3.