Brazilian Jiu-Jitsu is considered to be one of the best martial arts for self-defense, but as this video shows, it doesn’t always guarantee success in a fight.

The footage begins with a chaotic classroom brawl between two male teenagers reportedly fighting over a girl already well underway.

The larger teen in the red jumper has by this stage shoved his rival in the gray hooded top onto a table and is now trying to hit him with punches.

However, the guy in the hoodie clearly knows Jiu-Jitsu and is managing to at least partially keep his attacker at bay using his legs as a makeshift open guard.

In one slick motion, Jiu-Jitsu Kid suddenly transitions into an armbar attempt from his back and looks to go belly-down with it.

At that stage a male teacher rushes in to try to break up the fight, but he’s not quick enough to stop what happens next.

Using brute force, Red Jumper manages to power out of the armbar by wrenching his still-attached rival off the table and then slamming him hard on the classroom floor several times.

The teacher is then finally able to get in-between the two students to bring an end to the altercation.

Neither seems badly hurt and both parties mouth off at each other before going their separate ways, with a suspension from school undoubtedly awaiting them in the near future.

This video shouldn’t put anyone off doing BJJ, it’s still an excellent martial art in a 1v1 situation and it did help the teen fend off his rival to some extent and emerge relatively unscathed, as well as mount an attack from a position that he’d otherwise have had few options from.

However it also demonstrates that in the real world you can be forced to adapt on the fly to unexpected variables that you wouldn’t encounter in the gym – like tables, chairs and hard surfaces.

That unpredictability is one of many reasons why it’s always best to avoid fighting unless you are left with no other alternative than to defend yourself.