Protesters invaded the pitch at Hamilton's Rugby Park to force the cancellation of the South Africa v Waikato fixture, the second scheduled game of the 1981 Springbok tour of New Zealand.

Police arrested about 50 of the 350 demonstrators, but were caught in the crossfire between them and the rugby crowd that threw bottles and other objects at the interlopers. The match was finally called off, amid reports that a light plane had been stolen and was heading towards the park.

The Springbok tour was one of the most divisive episodes in NZ sporting history, as half the country mobilised to protest the apartheid policies of the South African government and others resented the potential interference of politics in sport. The tour was allowed to continue, but with protests at every stop.

After the Hamilton cancellation, rugby supporters waited outside the local police station for protesters to be released and assaulted them as they left. Later in the tour, the South Canterbury game was also called off and a low-flying plane dropped flour bombs on the final test at Eden Park.