Australia's Sharks can hardly believe how they pulled off a remarkable landmark water polo triumph, devouring two-time defending Olympic gold medallists Serbia in a Games sensation at the Paris Aquatics Centre.

For the first time in 18 attempts, coach Tim Hamill's men finally beat one of the sport's powerhouses, hammering them 8-3 to deliver a setback to the Serbs' hopes of winning a third title in succession.

It was an astonishing triumph for a raw Australian outfit featuring 10 Olympic newcomers as they suffocated the attacking prowess of a side who had blasted 16 goals past Japan in their previous match.

Hailed by 32-year-old captain Blake Edwards for pulling off an "amazing" victory, the Sharks could boast a host of heroes like Luke Pavillard, their sharp-shooting left-hander who blasted four goals in the first three periods.

But even he was happy to pass the MVP accolade to goalkeeper Nic Porter, who made nine outstanding saves from 12 shots rained in on him.

"When you've got Nic in goal behind you and he's playing that well, it feels like he fills all the holes," said Pavillard.

"Knowing Nic, he's probably going to be harsh on himself with the three that went in, but he's definitely my MVP today. He should be happy with his performance; I know we all are."

Porter deflected the praise, shrugging: "I just float there in the goal and try to get my arms up!

"But I can't remember the last time any team managed to restrict Serbia to three goals in a match. I'm a bit speechless."

It was the proudest moment for skipper Edwards, who was desperate for his side to rebound after their opening 9-5 defeat to European champs Spain.

Along with Pavillard's four tracers, Matt Byrnes chipped in with two goals, and Jacob Mercep and Charlie Negus netted one apiece as the Sharks came out snapping from the start in a bruising, physical contest.

"It was amazing. I can't say enough how proud I am of the boys," said Edwards.

Against all the odds, too, after Edwards' brother Lachlan was sent off early in the second period for a foul in this most physical of contests.

"That is another story for the boys to tell, without one of our best players and we were still able to grind it out for four quarters."

The Australians' excellence was only matched by a curiously error-ridden effort from the champions from Tokyo and Rio, who also struggled in their opening goal-fest before edging Japan 16-15.

Serb star man Dusan Mandic, who had scored seven against Japan, was marked so tightly he netted just two, the first coming just before the break when they were 6-0 down.

By then, the Sharks were already in dreamland with Pavillard, a 28-year-old from Kalgoorlie, having already notched his hat-trick with pin-point shooting.

His fourth followed soon after the break, with the Sharks perhaps now beginning to believe they really can lift a first ever men's Olympic water polo medal for Australia.