MELBOURNE, Australia -- Still smiling an hour later, France's Jeremy Chardy said he had just played "the most beautiful match" of his career.

The 25-year-old Frenchman staged the biggest upset so far at the Australian Open, beating No. 6 Juan Martin del Potro in a five-setter that lasted nearly four hours Saturday.  
"I feel so much emotion," Chardy said after the 6-3, 6-3, 6-7 (3), 3-6, 6-3 win. "It's a great moment for me. Everyone dreams of this."  
Chardy, who lost in the first round last year, frustrated del Potro with a tricky slice and a mix of drop shots, volleys and an inside-out forehand. One fast-paced rally in the third set sent the 6-foot-6 Argentine sprinting into the stands and hurdling a barricade.  
Del Potro, the 2009 U.S. Open champion, was seen as a potential challenger to the Big Three: No. 1 Novak Djokovic, No. 2 Roger Federer, No. 3 Andy Murray. In his first two matches, del Potro had dropped only 13 games -- the fewest among all men in the draw.  
But it was Chardy who dominated with 78 winners, including 44 on his forehand side. The big-hitting Del Potro had only 12 forehand winners in five sets.  
"The match was really tough," said del Potro, who rallied from two sets down to level the match but dropped his serve in the crucial eighth game of the final set. "In the end when he had the chance to break me, he did. I think that was key," said del Potro.  
"Jeremy played so strong for four hours," del Potro added. "He serves well. He made a lot of winners with the forehand, very good slices."  
Chardy reached the fourth round of a major once before -- five years ago at Roland Garros.  
"I played some tennis I never would have thought I was capable of playing," the No. 36-ranked Chardy said. "Five sets, to be here in a Grand Slam. It's the most beautiful match of my career."  
He's one of four French players to reach the fourth round, matching the country's record at Melbourne Park.  
Seventh-seeded Jo-Wilfried Tsonga and No. 9 Richard Gasquet also won their third-round matches Saturday, while No. 14 Gilles Simon was playing Gael Monfils later Saturday for a spot in the next round.  
Asked if a Frenchman could possibly win the Australian Open, Chardy smiled broadly.  
"Maybe me!" he said.