Frenchman Jeremy Chardy has caused the biggest upset of the Australian Open so far, dispatching men’s sixth seed Juan Martin del Potro in an epic third-round match at Melbourne Park.

Chardy was exceptional in opening up a two-set lead on Saturday, before the Argentine fought back to win the next two.

But the world No.36 broke del Potro’s serve in a tense final set to go 5-3 up, then served out the match 6-3 6-3 6-7 (7-3) 3-6 6-3 in three hours and 45 minutes on Hisense Arena.

“I don’t know what to say – I am so happy. I played my best tennis today,” a clearly surprised Chardy said after the match.

Briton Andy Murray overcame some nervous moments – including a second set break – before beating Lithuanian Ricardas Berankis 6-3 6-4 7-5.

Seventh seed Jo-Wilfried Tsonga was able to comfortably see off Slovenian Blaz Kavcic 6-2 6-1 6-4 in their third round clash.

He will meet countryman Richard Gasquet in the fourth round, after the ninth seed overcame an early scare from Croatian Ivan Dodig.

Dodig won the opening set, before the Frenchman blasted back to eventually win 4-6 6-3 7-6 (7-2) 6-0 in two hours, 25 minutes.

Playing in the third round of a Grand Slam for the first time, Dodig held a 3-1 advantage and break point in the second set before Gasquet launched his fightback.

All games went with serve in the third set, before Gasquet got the momentum to swing his way in the third set tie-break.

He then ran riot in the fourth set to secure a place in the next round.

Italian 21st seed Andrea Seppi beat Croatia’s Marin Cilic in five sets, 6-7 (7-2) 6-3 2-6 6-4 6-2 to also advance to the fourth round.