The pace, power and class of Tonga, however, eventually took a toll.
Tonga struck back almost immediately from a scrum with Tupou’s first try, but Wales was still in front nearing halftime.
The game took a momentum shift when star second rower David Fifita entered the action from the bench and his close-range try on 37 minutes put Tonga in front for the first time.
Wales’ defense cracked again two minutes later when second-rower Keaon Koloamatangi, who scored Tonga’s late match-winner against PNG, went through a gap for their third try. Tui Lolohea’s second conversion made it 16-6.
That quickly became 22-6 when fullback Tesi Niu wriggled free from Wales’ futile attempts to wrestle him to the ground for Tonga’s fourth try.
Wales prevented Lolohea grounding the ball when he forced his way to the line, but center Siosifa Talakai got Tupou over for his second try on the hour.
The pair produced a copybook move to enable Tupou to complete his hat trick. He had a fourth try disallowed for obstruction.