Tonga's thrilling 22-16 victory at Leigh Sports Village kept alive their hopes of topping Group C while the Cook Islands' second consecutive defeat means the USA Tomahawks are guaranteed to finish top of Group D.
That almost certainly means an unlikely quarter-final for the Americans with tournament favourites Australia in Wrexham on November 16.
The result was cruel on Cook Islands winger Chris Taripo, who scored all his side's points and delighted the stadium-record crowd of 8,544 with a superb hat-trick of tries that earned him the man-of-the-match award.
The Cook Islands conceded the game's first try to second rower Sika Manu after six minutes but the excellent Taripo went over for two tries in seven minutes and also kicked a goal to put his side 10-6 up.
The Newtown Jets player twice demonstrated clinical finishing after kicks from Isaac John and Drury Low prized open the Tongan defence.
The underdogs were good value for their lead but they were powerless to stop rampaging forward Jason Taumololo, who crashed over for a 31st-minute try to restore Tonga's lead, and blockbusting centre Konrad Hurrell, who bashed his way over for a third try just before half-time.
Sydney Roosters stand-off Samsoni Langi kicked three goals as the Tongans led 18-10 at the break but the game was back in the balance within three minutes of the re-start when Taripo produced a brilliant flying finish at the corner to take Low's pass and complete his hat-trick.
The winger added the touchline conversion for good measure to cut the gap to just two points but Tonga opened up a six-point lead when left winger Jorge Taufua squeezed over at the corner on the hour.
The Cook Islands never gave up hope, however, and Tonga were forced into some desperate defence in an enthralling final quarter.
Right winger Jordan Rapana dropped the ball over the line and substitute Hikule'o Malu had a try disallowed as Cook Islands fought magnificently to the end.
- Sports & Recreation
- Cook Islands