Last updated on .From the section Mixed Martial Arts

Polyana Viana (right) has won 10 of her 12 mixed martial arts fights

Warning: Contains graphic image below

A man has found out the hard way that it's a bad idea to try and rob an MMA athlete.

UFC fighter Polyana Viana was waiting outside her Rio de Janeiro apartment on Saturday, when the thief approached and threatened to take her phone.

Realising the danger, the Brazilian strawweight took matters into her own hands, using her MMA skills to knock the man down and keep him immobilised until the police arrived.

"He said: 'Give me the phone. Don't try to react, because I'm armed'," Viana told MMA Junkie external-link .

"Then he put his hand over [a gun], but I realised it was too soft.

"So I stood up. I threw two punches and a kick. He fell, then I caught him in a rear naked choke. Then I sat him down and said, 'Now we'll wait for the police.'"

Viana, 26, has a 10-2 MMA record. Her last fight ended in a decision loss to JJ Aldrich at UFC 227 last August.