Western Force led in the first half 10-7 but the ‘Ikale Tahi proved too strong in the second half led by fly half Kurt Morath and scrum half Sonatane Takulua.
The Tongans stuck to Coach Toutai Kefu’s game plan being direct and physical.
The stadium was packed with fans who managed to keep dry in the rain, while other fans in the outer area were drenched but stayed to the end.
Some fans including students from Queen Salote College, who cheered the Force on, sat in the rain waiting for hours before the match.
The ‘Ikale Tahi will now travel to New Zealand where they will take on Fiji at Eden Park on 31 August and the All Blacks in Hamilton on 7 September before they head to the Rugby World Cup held in Japan.