Brazilian jiu jitsu great and eight-time world champion Leandro Lo died after being shot in the head at a club in Sao Paulo.
The 33-year-old was out with his friends on Sunday for a concert at the Clube Siria, when a gunman approached them and began making threatening gestures with a bottle.
Lo reportedly immobilised the man by pinning him to the ground in an effort to "calm him down".
Iva Siqueira Junior, the athlete's lawyer, told AFP that Lo pinned the man to the ground "to stop the situation and avoid a fight".
Lo's friends then helped both the men up and asked the attacker to leave. "At that exact moment, the guy allegedly turned around, pulled out a gun and shot Leandro in the head," the lawyer added.
Lo was already lying on the floor with the gunshot wound when the suspect kicked Lo twice, the lawyer said.
He was rushed to a hospital but declared brain dead hours later.
The suspect, identified as an off-duty police officer aged 30, initially fled the scene, but later handed himself over to the authorities.
He has been detained for 30 days pending further investigation.
The International Brazilian Jiu-Jitsu Federation called Lo "one of the greatest athletes our sport has ever produced".
"An example of a true black belt, martial artist and champion on and off the mats," the federation tweeted.
"The word legend is thrown around way too much in sports but it can’t be thrown around enough when it comes to your name in jiu jitsu," wrote MMA artist Josh Thomson.
“Wow. Unbelievably tragic news about Leandro Lo. RIP to a jiu jitsu legend. Shocking,” shared referee Marc Goddard.
