The original concept of the Ultimate Fighting Championship was to put athletes from different martial arts against each other to see which disciple would be more effective in a no rules fight.

The obvious winner at the time was Brazilian jiu-jitsu. Modern mixed martial arts has involved to include weight classes, rules, and the athletes have to be well-discplined in multiple martial arts or combat sports to succeed.

In this video, a BJJ blackbelt wants to test himself in a controlled environment against a stand-up specialist, in this case a muay thai expert.

It is not a no rules fight and the intensity is not quite a real fight, but at least in this case the BJJ practioner is able to defeat the Muay Thai fighter more than once:

The bell rings and the two touch gloves for the first time. The muay thai fighter starts out strong landing some good legs kicks and punching combinations. But as soon as he throws a head kick, the BJJ fighter blocks and immediately follows his kick back into a takedown. He is able to take the muay thai fighter down, but unable to keep him down, pulls guard. The muay thai starts to land some ground and pound, but the BJJ fighter is able to get back to his feet where he is immediately met with another barrage of kicks and punches.

Again the BJJ fighter shoots a takedown is able to get the fight to the mat and again the muay thai fighter is able to push him away and get the fight standing again. The stand up fighter sends the BJJ fighter to mat with a strong front kick, but after getting up shoots yet another takedown, but this time is able to get to the back of the muay thai fighter, and transition to side mount. But the Muay Thai fighter is strong and again gets to his feet.

After a couple more scrambles, the two end the match. The BJJ fighter was not able to get the fight to a position he could secure a submission.