That fire power wasn't enough to hold out Fiji who were playing a test at home for the first time in almost three years.
Fiji made an explosive start scoring three tries to lead 19-0 after only 24 minutes. France-based Tevita Ratuvua scored the opening try in the seventh minute and winger Jiuta Wainiqolo added the second three minutes later.
Fiji took advantage of Tonga's shaky scrum and lineout to control possession in the early stages of the match.
Center Kaliveti Ravouvou finished a movement which swept almost the length of the field in the 24th minute for Fiji's third try. The move began when Fiji turnover over a Tonga lineout five meters from their goal line and Ravouvou pounced on the ball when it was knocked back towards the Tonga goal line.
Setareki Tuicuvu scored the first try of the second half after lead-up work by Fiji captain Waisea Nayacalevu and winger Vinaya Habosi completed the scoring, running off a pass from Suliasi Vunivalu.
Earlier, Nigel Ah-Wong scored an intercept try two minutes from fulltime to give Samoa a 31-26 win over Australia A in the opening match of the tournament.
Samoa led 19-7 at halftime but Australia A rallied to level the score at 26-26 with a try to James Tuttle in 77th minute.
Australia A swept onto attack from the re-start but Ah-Wong snatched a pass from Lalakai Foketi out of the air and dashed almost 80 meters to score the winning try, his second of the match.
Samoa opened the scoring after only five minutes with a try to hooker Seilala Lam and extended its lead in the 21st minute with Ah-Wong's first try.
Back rower Fraser McReight scored for Australia before Samoa increased its lead to 19-7 at halftime with a try to D'Angelo Leuila.
McReight's second try and another to Ryan Longergan allowed Australia A to level the score midway through the second half. Samoa drew ahead again in the 69th with a try to Jonathan Taumateine, leading 26-19 until Tuttle's late try and Ah-Wong's second decided the match.
- AP