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Sean Cerveny- Co-Owner & Head Instructor


Sean Cerveny is a Cesar Gracie Jiu Jitsu black belt as well as a currently undefeated pro MMA fighter (5-0) and professional boxer. 

His grappling career began when he started wrestling as a young kid. He soon discovered Brazilian Jiu Jitsu; and in hopes of becoming a pro MMA fighter, he started training under Cesar Gracie with Darin Cooley, Nick and Nate Diaz as well as many other notable fighters in Stockton, CA where he is originally from. 

He has been training Jiu Jitsu, Sambo, and mixed martial arts for over a decade and other forms of grappling for much longer . He has competed in many Jiu Jitsu and wrestling tournaments since he was 10 years old. 

He is undefeated as a professional mixed martial artist. He has fought internationally as well as on the regional level on shows such as Fury Fighting Championship and Legacy Fighting Alliance to name a couple. His fights have been televised on UFC Fight Pass and ESPN+. Having finished all his fights in the first round with unorthodox finishes, Cerveny is widely recognized as a leg lock specialist.

Never turning down a challenge and an opportunity to test himself, he's also fought as a professional boxer, including a bout on Top Rank boxing.

Before moving to Maine with his wife to pursue their dreams of opening a gym, Sean has lived in California and Texas where he's taught both adults and kids classes and has over 10 years of teaching experience. 

In addition to a successful martial arts career, he has also recently started a new career in law enforcement. He is currently a full time police officer.


Grace Cerveny- Co-Owner & Coach


Grace started Jiu Jitsu in 2015 at Graciefighter Manteca, in California for the purpose of learning practical self defense and staying in shape. She quickly developed a love for the art and has been training for almost a decade. She has trained in California and Texas before moving to Maine. 

She is currently a brown belt under the lineage of Cesar Gracie and received her brown belt from Sean Cerveny in May 2024.

She currently teaches all of our beginner classes, kids classes and some of our all levels classes. She also runs our fitness and conditioning programs. 



What Is Lineage?

Belt lineage is who your instructors got their black belt from. Think of it as a family tree that can be traced all the way back to the beginnings of Jiu Jitsu, which we know started with Mitsuyo Maeda, Carlos Gracie and Helio Gracie. Anyone who trains Jiu Jitsu should be able to trace their roots to the beginning. 

Why Does Lineage Matter?

Lineage is not just a family tree though. Lineage, first and foremost is a way to verify the legitimacy of your Jiu Jitsu academy and your instructors. When you train somewhere, you want to know that you are not learning from some self taught YouTube black belt or self proclaimed fake black belt who trained a different martial art that supposedly "had Jiu Jitsu in it".  Every person who received a belt in Jiu Jitsu should right away be able to tell you who promoted them to that belt level. 

More than just a basic level verification, lineage is also quality control. Just because someone can verify their Jiu Jitsu roots, doesn't mean their lineage upholds high standards. Some lineages are known for producing great fighters and competitors and having high standards for belt promotions, and others are known for being watered down and even selling online belts. Knowing lineage can help new students find a gym with a good reputation and high standards. 


Lastly, lineage can also help you choose the right gym for your individual goals. Just because a Jiu Jitsu gym is legit and offers high quality instruction, it does not mean it is the right one for you. For example, the training at a self defense/ MMA focused gym will be a different than a sport Jiu Jitsu focused gym. 

You will still learn legit Jiu Jitsu at either type of gym, but knowing the lineage can help students find the right gym for them based on their individual goals. 

Our Lineage

At Graciefighter Caribou, we represent and uphold the high standards of  Cesar Gracie Jiu Jitsu. 


Our Lineage is:

Mitsuyo Maeda >  Carlos Gracie Sr.  >  Robson Gracie > Cesar Gracie >

Nick Diaz > Darin Cooley  - Sean Cerveny


Cesar Gracie 


Cesar Gracie is known worldwide as a legend in Brazilian Jiu-Jitsu and MMA instruction. Born in 1966, he is related to  Carlos Gracie Senior (the Gracie Jiu-Jitsu founder) by way of his mother, Sonja Gracie-Gronning. His parents separated when Cesar was still a toddler and Cesar was raised solely by the Gracie side of the family with grappling being a natural part of his upbringing.

Cesar Gracie is a Brazilian Jiu Jitsu black belt under Carlos Gracie Senior's son Robson Gracie. After receiving his black belt in 1992, Cesar moved to Northern California where he opened his own academy, becoming the 3rd Gracie in North America to open a Jiu Jitsu gym. His gym became one of the most successful Jiu Jitsu and MMA gyms in the world, producing top fighters including Jake Shields, Yancy Medeiros, Gilbert Melendez, David Terrell and most notably, Nick and Nate Diaz among many others. 

Nick Diaz

Nick Diaz is a professional Mixed martial arts fighter and has fought in UFC, PRIDE, Strikeforce, EliteXC, World Extreme Cagefighting (WEC), DREAM, and Shooto. He was promoted to black belt in Jiu Jitsu by Cesar Gracie on May 8th, 2007 

Darin Cooley

Darin Cooley holds a Black Belt under the prestigious Cesar Gracie , who is universally known for having some of the strictest standards in Jiu Jitsu. He has been training and teaching Jiu Jitsu for almost 20 years, a long time training partner to well- known fighters such as Nick and Nate Diaz. Cooley is also an accomplished professional MMA Fighter, Jiu Jitsu competitor and college wrestler. He has since turned his focus to teaching full time and runs his own Jiu Jitsu gym in Manteca, CA.


Val Ignatov


Val Ignatov is a Combat Sambo legend and he has played an important role in forming the GracieFighter team since its early days.  

Ignatov is originally from Bulgaria. He started training Sambo at age 11, a Russian martial art that resembles wrestling and focuses on throws and submissions. He went on to win a national championship at 16 years old, and was invited to join the Bulgarian national team, capturing more titles during this time.  At age 18, he was required to join the army where he was sent to a special training program in Combat Sambo and was certified as an instructor. He was a champion in a country where Sambo was a respected national sport.

In 1996, he moved to the United States and started training in Lodi, Northern California where he met Cesar Gracie. At the time, Cesar was one of the first Jiu Jitsu guys who were open to training with a Sambo guy. Many of the other Jiu Jitsu schools he went to didn't accept his Sambo grappling style which included leglocks. 

Ignatov trained with Nick Diaz, Nate Diaz, Gilbert Melendez, Jake Shields, Dave Terrell and the rest of the Caesar Gracie Fight Team when they were just starting out. He has fought in the UFC in its early days. 

Ignatov is also a Cesar Gracie Jiu Jitsu black belt. 


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