Rugby: Williams heading back into the ring

All Black Sonny Bill Williams will step back into the boxing ring for his third professional fight, the Stuff website reports.

Stuff says the fight is believed to be taking place next year, just months before the Rugby World Cup in New Zealand in September.

Williams, who walked out on the Bulldogs rugby league club in 2008, will reportedly hold a press conference tomorrow in Sydney to outline details of the bout.

In attendance will be Aussi boxer Anthony Mundine, a good friend of the All Black midfielder.

Williams has twice previously fought on the undercards of Mundine's KO To Drugs events.

His most recent bout was on June 30 in Brisbane.