The 28-year-old Japanese fighter picked up a shocking injury during his bout against Johnny Case - who went on to win the fight due to a technical knockout.
Yachi was forced to stop by doctors after Case left him with a massive wound on his right eye. Blood gushed from the injury, while the whole area swelled up to sickening levels - the combination of which left Yachi unable to see.
Yusuke Yachi was left with a devastating eye injury during his fight with Johnny Case. Credit: RIZIN
Fight fans watching at home rushed to social media to comment on the injury.
One wrote: "Yachi's eye has a nasty hematoma that has been split open. His eye is a wreck."
While another added: "Man, that right eye of Yusuke Yachi was nasty!" You can say that again, mate.
According to reports, Yachi was taken to hospital following the fight, and missed out on post-match interviews.
Although the injury was certainly a grim talking-point, it was, of course, Mayweather versus Nasukawa that had everyone talking.
The man they call 'Money' was paid an obscene £$9 million for what turned out to be less than three minutes' work - not bad, eh?
Bragging about the pay-packet he'd be picking up on social media, Mayweather wrote: "What if I told you I was making $9,000,000 for 9 minutes of sparring in Tokyo Japan would you do the same if you were me? I like to call it a 9-minute walk thru."
Twenty-year-old Nasukawa was knocked down three times in the first round, prompting his side to throw in the towel.
After the fight, Mayweather said: "It was all about entertainment. We had fun. Tokyo, you were amazing, but I'm still retired. We're both still undefeated. Tenshin is still a champion and a great fighter."
The New Year's Eve exhibition match at Saitama Super Arena in Japan was part of RIZIN's MMA card and consisted of three three-minute rounds, but, of course, it didn't get that far before Nasukawa's side called time on the fight.
Although officially retired, Mayweather has said he will continue to take part in exhibition fights, like the one in Toyoko today. Well, when he's picked up a million dollars a minute, who can blame him?
Featured Image Credit: RIZIN