Melbourne Rebels forward Amanaki Mafi was arrested and faces assault charges after an altercation with teammate Lopeti Timani in New Zealand, Rugby Australia said on Sunday.
The brawl followed the Rebels' 43-37 Super Rugby loss to the Otago Highlanders in Dunedin on Saturday.
"Rugby Australia and the Melbourne Rebels are aware of an incident involving Rebels players Amanaki Mafi and Lopeti Timani in Dunedin overnight," RA said in a statement.
"Both players remain in New Zealand with Mafi currently in police custody following an altercation between the two players."
No other players were involved in the altercation, the statement added.
A police spokeswoman told foxsports.com.au that a "man has been charged with injuring with intent to injure following an alleged assault in South Dunedin last night" and was due to appear in court on Monday.
Timani received "moderate injuries" in the altercation but did not go to hospital, she said.
Mafi, 28, represented Tonga at the 2009 Under-20 World Cup in Japan, and after moving there was selected for the Japanese national side in 2014.
The powerful No. 8 played in the 2015 World Cup in England including Japan's memorable 34-32 upset of South Africa in Brighton.
Amanaki Mafi will appear in court on Monday after allegedly assaulting Rebels teammate Lopeti Timani