Kiwi boxer David Nyika has revealed the mental hurdles he's battled since suffering his first professional loss in devastating fashion

The two-time Commonwealth Games champion will fight compatriot Nik "The Greek" Charalampous on next month's Sonny Bill Williams-Paul Gallen undercard in Sydney.

The bout will be Nyika's first since a brutal knockout defeat by IBF cruiserweight champion Jai Opetaia in January.

Nyika says his resilience is being tested.