Portugal has secured a famous 24-23 Rugby World Cup victory over Fiji, but it was not enough to save the Wallabies, who have crashed out of the tournament.

The Wallabies needed a miracle to progress to the knockout rounds, requiring Portugal to beat Fiji and deny their Pacific rivals a losing bonus point.

And although Os Lobos completed the first part of that bargain, their narrow victory still handed Fiji the losing bonus point they needed to scrape into the quarterfinals for the third time in their history.

"It's incredible. It's unbelievable, they always find resources I never expect," departing head coach Patrice Lagisquet said.

"The way they could score, it's amazing. Even if we work a lot to be able to do things like that, they still surprise me after four years.

"It is an incredible group, an incredible team and they are players who are really talented."

A cagey but thoroughly entertaining first half saw the two teams enter the sheds locked at 3-3, but Portugal burst the game open in the second half when Raffaele Sorti crossed for the opening try of the game.

Rodrigo Marta launched another attack soon after as Portugal looked to push their advantage, but Sireli Mawqala's stunning counterattack resulted in Levani Botia levelling the scores once again.

Botia was then sent to the sin bin for a high tackle and Portugal made their extra man advantage count, Francisco Fernandes burrowing over.

Fiji hit back again through replacement prop Mesaka Doge, before two Frank Lomani penalties gave Fiji a 23-17 lead heading into the final minutes.

However, Marta sent the crowd wild with a final-minute score to bring Os Lobos to within a point and, on the same ground where a last-gasp penalty against Georgia fell agonisingly wide, Samuel Marque nailed the sideline conversion to hand Portugal a famous win.

"I think it's the best moment of my life," player of the match Nicolas Martins said post-match after Portugal celebrated with their multitude of supporters.

Fiji will play England in the quarterfinals in Marseille next week, but that achievement was overshadowed by the joyous scenes among the Portugal players and supporters at full time.

"Congratulations to Portugal, hats off to them, they really played well today," Waisea Nayacevelu said.

"We didn't execute a lot of our plays, dropped a lot of balls and they took advantage of our mistakes.

"I salute them and congratulate them on the win.