Dylan Nacass, 23, was surfing at Bells Beach, about 1.5 hours from Melbourne, when the shark attacked on Friday, Nine News said.
Video footage shows a shark swimming up behind two men as they paddle desperately to get away.
Nacass told Nine the shark latched onto his leg until he punched it twice and he was released from its jaws.
“I punched him one time, he stays in my legs. Two times, after, he go,” he said.
Local man Matt Sedunary rushed to the Frenchman’s aid after realising he was in distress.
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“He started screaming – I honestly thought he was joking around with his friends,” he told Nine, adding he “wasn’t going to ditch him”.
“Most people would do the same thing.”
The incident was captured by Australian man Graham Blade, who was filming from a nearby lookout at the world-famous surf break.
“I actually saw it pop up behind him and knew it was real,” Blade told Nine.
Nacass walked away with only puncture wounds to his right leg that required stitches. Both men made it back to shore, unaware that the shark was still behind them as they made their way.
Local shark watch groups posted about the incident, garnering over a 1, ooo likes and hundreds of comments as social media users were left reeling by the near miss.
“Definitely looked like there were two at one point,” one commenter speculated.
‘Shark at Southside not keeping its 1.5m distance’. Insta @grahamblade Video screen capture from at around 4pm…
Posted by Dorsal Shark Reports – Australia on Friday, May 8, 2020
At this stage, it’s unclear what species of shark was responsible for the incident.
Australia has one of the world’s highest incidences of shark attacks, but fatalities are rare.
There were 27 maulings but no fatalities off Australia last year, according to data from Sydney’s Taronga Zoo.
Despite his ordeal, Nacass said he was eager to return to the water once his injuries have healed.
“I really want to go back soon,” he said. “Just when my leg, it’s OK. I’m going to go back to surf soon.”
– with wires