‘American Ninja’ Nate Diaz scored the biggest victory of his career at UFC 196 against Irish superstar Conor McGregor. Diaz’s win, an upset for a lot of people, immediately prompted fans, observers, and celebrities too, to react. Everyone felt like they HAD something to say, even if they clearly didn’t know much about the sport of MMA. Among one of the most talked about post-fight reactions was none other than Justin Bieber’s.

The young superstar took to Instagram to share his thoughts about the fight, and stated that McGregor is a true champion who fights with style in finesse while calling Diaz’s style terrible.

Uh oh. Bieber’s words didn’t please Nate Diaz, to say the least. The UFC fighter is well-known for standing his ground against whoever feels likes dissing him, celebrity or not. It thus prompted him to took to social media to respond to Bieber’s criticism by telling him: Shut your f**king ass up.

The feud between the UFC fighter and Justin Bieber (of all people) sparked a lot of discussion inside MMA circles, and even among established mainstream outlets. It’s not every day that a music superstar feuds with an ‘American Ninja’, after all. Diaz recently did an interview for Rolling Stone and here is what he had to say: Bieber don’t watch the sport; he don’t know the sport. I’ve seen a couple other people too, Drake, all these other guys that are stating their opinion, how are you going to state your opinion when you don’t know sh*t? You’re just showing your lack of knowledge on the sport.

Well, he has a point.

Check out this Nate Diaz interview where he talks about the McGregor fight, and, of course, his meeting with Justin Bieber:

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The thing is, the feud between Nate Diaz seems to have died down. The two actually met face-to-face at a concert after-party at Warwick nightclub in Hollywood on Wednesday and it looks like they’re totally cool now.