Fly-half John Manu was the star of the show as Fiji overcame fierce resistance from Pacific rivals Tonga to win the Oceania U20 Trophy in Suva on Saturday.

Manu, a second-half hat-trick scorer in Fiji’s earlier 50-3 win over the Cook Islands, scored the second of Fiji’s two tries and kicked eight points as the home side withstood a spirited comeback from Tonga.

The 18-13 victory ensured Fiji of their place at World Rugby U20 Trophy 2017 in Montevideo, Uruguay.

A Fiji win looked a formality when they stormed into a 12-0 lead in as many minutes. Centre Filimoni Savou was the first to cross the whitewash after a neat handling move down the short side before Manu added another, which he converted.

But Tonga clawed their way back into the game and when inside centre Sione Va’eno scored and Tevita 'Ekuasi tagged on the extras, there was only five points in it.

'Ekuasi cut the deficit to one point shortly after the re-start and could have given Tonga the lead had he landed his next penalty but the attempt went wide.

Two penalties from Manu, on 50 and 66 minutes, saw Fiji pull more than one score ahead and despite their best efforts Tonga could only muster a penalty from the boot of replacement Adrea Navelinikuro as they fell just short of springing a surprise.

Fiji will now join hosts Uruguay, South American qualifiers Chile, African U19 champions Namibia and Japan, who were relegated from the World Rugby U20 Championship after a bottom-place finish in 2016, as confirmed participants at next year's  U20 Trophy.

Oceania U20 Trophy Results:

Fiji 50-3 Cook Islands, Tonga 50-12 Cook Islands, Tonga 13-18 Fiji

Oceania U20 Trophy Final Standings:

1. Fiji 9 pts, 2. Tonga 6 pts, 3. Cook Islands 0 pts