BJJ wins again.

A former Australian jiu-jitsu champion has saved a tourist from being robbed on a Sydney street after wrestling with the alleged assailant for 15 minutes while flesh was allegedly bitten out of his arm and capsicum spray was shot in his eyes.

Thiago Braga, 32, was driving on Harris Street, Pyrmont, on Saturday morning when he came across a distressed tourist, yelling in pain, rubbing his eyes and clutching for his stolen bag.

The 23-year-old Indonesian man had allegedly been capsicum sprayed by another man while out for a morning walk.

Seeing the victim's distress, Mr Braga pulled over in his car, ran to the closest convenience store and grabbed some water to flush out the man's eyes.

Unfortunately for the man who had allegedly stolen the bag, Mr Braga also found him.

Anthony Ryder, 39, from Marrickville, was allegedly rummaging through the victim's bag on Harris Street when Mr Braga, originally from Brazil, pounced.

He threw himself at the man, giving chase and tackling him in Ada Place before pulling him into a jiu-jitsu grapple.

Mr Ryder allegedly sank his teeth into Mr Braga's arm, ripped out a piece of flesh and squirted capsicum spray in his eyes.

Despite searing pain, Mr Braga continued to hold the man on the bitumen of the Pyrmont laneway.

"I couldn't see or breathe, I was just trying to contain him," Mr Braga said.

The pair wrestled for more than 15 minutes before police arrived.

Jiu-jitsu is a martial art especially suited to wrestling; it is defined as the art of grappling on the ground.

"I was really worried about not hurting him too much," he said. "I didn't want to become the aggressor. After 17 years of training, I'm just lucky I have the skills to be able to control people in those situations".

The alleged victim of the theft who did not want to be identified is understood to be relieved to have his bag, containing his passport and wallet, returned to him.

Mr Braga is keen to get straight back to training his students in his Legacy Jiu-Jitsu programs in gyms across Sydney after spending the day getting treatment for his injuries.

Mr Ryder was charged with robbery while armed with a dangerous weapon, use of an offensive weapon to prevent lawful detention and assault occasioning actual bodily harm.

He faced Paramatta Bail court on Sunday morning and appeared via video link nursing a bandage to his face.

He did not apply for bail and it was formally refused. He is due to face Central Local Court on Thursday.