Tonga have prevailed 20-18 over Samoa in an epic World Cup contest in front of a record crowd of 29,411 at CommBank Stadium.

Both teams now head towards the semi-finals on the back of a pulsating contest that ebbed and flowed for the entire 80 minutes.

After the emotion of the pre-game war cries had settled it was Tonga who looked to have grabbed first points in the 13th minute when Dallin Watene-Zelezniak launched himself for the corner but replays showed his foot had grazed the sideline.

Four minutes later Tonga went close again when Jojo Fifita had a chance in the left-hand corner but desperate defence from Stephen Crichton denied him.

Come the 24th minute and Fifita returned serve when he jammed in and forced an error from Crichton just as the Samoa centre looked certain to score.

After 27 pulsating minutes of action it was Rob Toia who broke the deadlock with a stunning solo try from 45 metres out.

The Tonga centre was put into space by a superb flick pass from Haumole Olakau'atu and then displayed his speed and swerve to leave Hamiso Tabuai-Fidow and Sua Fa'alogo in his wake. With Isaiya Katoa's conversion Tonga had a 6-0 lead.

A penalty goal to Katoa in the 36th minute extended Tonga's lead to 8-0 before Samoa hit back through Brian To'o courtesy of a piece of Crichton brilliance.

The try came after Jarome Luai launched a bomb which was tapped back by Tabuai-Fidow to Crichton and the champion centre got a miraculous flick pass away to To'o despite having three defenders hanging off him.

Ahead 8-4 at the break Tonga extended their lead in the 46th minute when Katoa and Tui Lolohea combined on the left edge with the five-eighth delivering a pinpoint long ball for Fifita to power into the corner. The conversion from Katoa made it 14-4.

Samoa struck back in the 52nd minute when To'o had a second try from another freakish pass this time from Chanel Harris-Tavita, who missed the conversion and grabbed at his hamstring after the kick and left the field immediately.

Four minutes later Samoa looked certain to score again but Benaiah Ioelu was somehow denied by Lehi Hopoate and Haumole Olakau'atu right on the goal line as they hurled themselves at the hooker and forced the ball loose.

With 17 minutes to play Samoa had their third try when Luai snuck down a short side and picked up Izack Tago who shifted it quickly to Fa'alogo who delivered the final pass for Tabuai-Fidow to race away and score. Ronald Volkman was unable to land the extras so Tonga retained the lead at 14-12.

All the momentum was now with Samoa and supersub Volkman busted through a couple of tackles to score after some brilliant hands from big men Junior Paulo and Spencer Leniu.

At 18-14 to Samoa the game had another twist when Addin Fonua-Blake took a pass one off the ruck and stampeded through Leniu and Connelly Lemuelu to tie it up and with Katoa's conversion the men in red had the lead back at 20-18.

With two minutes to play Samoa launched a raid on the left edge and Fa'alogo went agonisingly close but his foot grazed the sideline.

In the final minute Samoa again had a shot at stealing the win when Tabuai-Fidow flew high to bring down a bomb but his pass to Fa'alogo travelled forward and Tonga hung on for an emotional victory.