Actor and R&B singer Ray J suffered a rough knockout in a celebrity MMA match he starred in on Saturday amid his claim that he has only months left to live.

The 45-year-old singer took part in a UFC Apex event hosted by controversial livestreamer Adin Ross.

The 'Let It Go' singer - who made a famous sex tape with Kim Kardashian that launched her to eventual international recognition - faced off against YouTube icon Supa Hot Fire during the bout in Las Vegas.

Early in the second round, Supa Hot - a character created by Deshawn Raw - delivered a knockout blow to the hitmaker.

Ray J - real name William Ray Norwood Jr - appeared visibly stunned by the blow and fell against the ropes and onto the mat.

While he was able to get back up, he needed to sit on a stool - forcing the referee to end the match.

In a post-fight interview, Ray J appeared to suggest that the fight was supposed to be fixed in his favor - only for Supa Hot to not follow the plan.

'Damn bro … like that? For real … that's janky as f**k,' Ray J told his rival, seemingly in disbelief.  'I don't want to say too much because I don't want to get nobody in trouble, but damn … we took an L tonight.'

Ray J added, 'You know how much money we lost? Wow... wow.' 

This fight comes nearly four months after Ray J claimed he didn't have much longer left to live due to heart issues due to a history of heavy drinking and drug abuse.

He revealed that he is suffering from severe heart failure where the organ is only beating at '25 percent.'

'2027 is definitely a wrap for me,' the singer told social media in January. 'That's what they say.'

'I shouldn't have went this hard, bro,' he continued. 'My baby mama [his estranged wife, Princess Love] gonna be straight, my kids gonna be straight, if they wanna spend all the money, they can spend it.

'I did my part here. And damn, when it's all done, burn me, don't bury me.'

He had been hospitalized in Las Vegas, NV on January 6 for severe case of pneumonia and heart pains.

The Mississippi-born belter was prescribed eight medications to treat his condition and doctors have told him to prepare for a possible pacemaker or defibrillator - according to TMZ.

Bleeding eyes or retinal hemorrhages can reportedly reveal systemic vascular damage that can indicate an increased risk of heart failure.