Debutant Eremasi Radrodro scored the winning try six minutes from time as Fiji overhauled a 15-0 halftime deficit to open the Pacific Nations Cup with a 23-18 victory over Tonga in Suva.
Tonga, ranked 13th in the world, stunned their 11th-ranked hosts when first-half tries from scrumhalf Tane Takulua and winger Pila Iongi helped them to a healthy halftime lead.
Flyhalf Ben Volvola and number eight Neemia Soqeta crossed after the break and Seremaia Bai drew the Fijians level with his second penalty before flanker Radrodro touched down in the corner in the 74th minute.
Welshman Nigel Owens officiated in his 71st test to overhaul South Africa's Jonathan Kaplan as the most experienced international referee of all time.
Tonga, Fiji and Samoa are competing for this year's Pacific Nations Cup, which forms part of the qualifying process for the 2019 World Cup in Japan.
Samoa, who were held 19-19 by Georgia in Apia earlier in the day, will play Fiji in the second round of the Cup next Saturday.