The Ultimate Fighter: American Top Team vs. Blackzilians (also known as The Ultimate Fighter 21) was the twenty-first installment of the Ultimate Fighting Championship (UFC)-produced reality television series The Ultimate Fighter. This season was the first to feature a gym vs. gym theme.

The series was officially announced by the UFC on February 28, 2015. For the first time ever, the UFC reality series featured a format pitting two of the sport's top gyms – American Top Team and the Blackzilians – against one another. The season was filmed in South Florida, where the two camps sit just miles apart, and the competitors were welterweights from each facility. An amount of $500,000 was earned throughout the season based on wins and losses for the winning gym.

Dan Lambert heads the ATT team, and rival Glenn Robinson heads the Blackzilians club. The series prominently features the rivalry between the two camps, which developed in 2011 after a band of ATT fighters defected and started their own camp with Robinson, who is the gym's owner but not their head coach. The two gyms are located just 20 minutes apart. The teams were made up of eight up-and-coming welterweights from each gym. The 16 men shared a house in the Miami/Fort Lauderdale area but instead of training amongst each other, the athletes still worked with their coaches at their respective gyms. The actual fights took place at American Top Team in Coconut Creek and the Blackzilians' Jaco Hybrid Training Center in Boca Raton. The winning fighter earned home gym control for his team for the next bout. Opponents were not revealed until weigh-ins for the first time.

Cast

Teams

American Top Team Dan Lambert, Gym Owner Ricardo Liborio Marcus "Conan" Silveira Mike Brown Din Thomas Brian Harris Steve Bruno Robbie Lawler

Blackzilians Glenn Robinson, Gym Owner Jorge Santiago Greg Jones Rashad Evans Tyrone Spong André Benkei Corey Peacock Douglas Kalman Jason Gochez Michael Johnson

Fighters American Top Team Marcelo Alfaya, Steve Carl, Nathan Coy, Michael Graves, Hayder Hassan, Sabah Homasi, Uros Jurisic, Steve Montgomery. *Montgomery was removed from the competition on episode 4 due to medical reasons. He was replaced by Cristiano Souza on episode 7.

Blackzilians Valdir Araújo, Carrington Banks, Luiz Firmino, Jason Jackson, Vicente Luque, Andrews Nakahara, Felipe Portela, Kamaru Usman. *Nakahara was forced out of the competition on episode 7 due to a medical suspension. He was replaced by Alexandre Pimentel.

Episodes Episode 1: Rumble in South Florida (April 22, 2015) For the first time ever The Ultimate Fighter will be contested outside of Las Vegas, this time at South Florida. Both gyms, American Top Team and Blackzilians, are introduced, as well as their owners. They both share their stories about the inception of their gyms, including Blackzilians formation, as some of ATT fighters back then defected to the soon-to-be formed gym. Dana White comments on the fact that each owner will choose one fighter but their opponents will not be revealed until the weigh ins. There will be 12 fights in the first round and a fighter can fight up to three times or not at all. He also explains the format of the team competition this season: the first 4 fights will be worth 25 points each, the next 4 fights 50 points each and the final 4 fights will be worth 100 points each. The team with the most points at the end of the 12 fights will earn $200,000. After that, they move to the finale. For a fighter to be eligible, he must have fought two times during the regular season (12 fights). The winning fighter gets $300,000 for their gym. Each gym presents their fighter picks for the tournament. The teams arrive at the mansion in boats and are later greeted by White. He flips a coin (blue for ATT, black for the Blackzilians) of each team to determine the gym that will host the first fight, reminding them that the winner of each fight gets the home gym advantage for the next one. The Blackzilians win the coin toss. Dan Lambert explains to ATT's fighters all the aspects of the season. Glenn Robinson hosts the Blackzilians at his house as they watch their teammate, Anthony "Rumble" Johnson, defeat Alexander Gustafsson at the main event of UFC on Fox: Gustafsson vs. Johnson. ATT picks Michael Graves for their first fight. The Blackzilians picks Kamarudeen Usman. Later, both fighters make weight successfully. Kamarudeen Usman defeated Michael Graves via majority decision (20–18, 20–18, 19–19) after two rounds. After the fight, Hayder Hassan challenged Usman to a fight.

Episode 2: Battle Lines Drawn (April 29, 2015) Michael Graves expresses his sour feeling due to his loss on the last and also his opinion that he gave an opportunity for the Blackzilians to gain confidence. His teammates talk about the fact that they have all faced losses before and Graves never has. Due to that, Steve Carl believes his teammate will now have less pressure on his shoulders. Graves is supported by Nathan Coy and Hayder Hassan, who both say that they are all motivated to defeat their opponents. Hassan tries to work mind games on Kamarudeen Usman, but he does not want to take part in it. Later, both fighters comment on the situation with their teammates. After analyzing several options, ATT picks Uros Jurisic. The Blackzilians also consider many options, ultimately picking Luiz "Buscapé" Firmino. During a training session at the Fighter's House gym, Usman gets frustrated and angry at Jason Jackson. He leaves the session showing off his anger, but later calms down and apologizes to Jackson. Both fighters make weight and after that, Dan Lambert and Glenn Robinson exchange heated words during a confrontation. Luiz Firmino defeated Uros Jurisic via unanimous decision (20–18, 20–18, 20–18) after two rounds.

Episode 3: Settling the Score (May 6, 2015) Valdir "BBMonstro" Araújo complains about a stolen bottle of red wine. He believes that somebody from ATT stole it, but all of them deny it. In turn, Michael Graves confirms to Nathan Coy in a poker match that he drank the wine earlier. Steve Carl comments that his teammate has been doing deliberate things ever since he lost the first fight. After analyzing their options, ATT believes its time to change the game using their veterans and they pick Carl, a former WSOF Welterweight champion. The Blackzilians analyze their training and recovery to decide their next pick. After considering those aspects and his experience, they pick Araújo, who has formerly fought UFC middleweight champion Chris Weidman. Sabah Homasi talks to Steve Montgomery about Araújo's accusations days earlier and Graves' unadmitted guilt over drinking the wine. They both believe that Graves is being weak at the moment and that he needs to pull himself up. During weigh-ins, Carl weighs in at 171.75 lb on his first attempt and must make 171 within one hour. He goes to the Blackzilians' locker room to use their sauna and Michael Johnson does not like the fact that they are helping their rival. Tyrone Spong did not know that and does not like it as well. He discusses the issue with the athletic commission representative and later enters the locker room to confront ATT. Spong and Johnson demand that Carl and ATT leave the locker room. Dan Lambert and Coy argue with them about letting Carl stay as they would do the same if it was the opposite case. Spong says there are no rules about that and Coy mentions that "no rules" means that they will stay until their teammate cuts the remaining weight, which leads to a heated confrontation between the two of them. In the end, Carl weighs in at 170 lb. Valdir Araújo defeated Steve Carl via submission (guillotine choke) in the second round.

Episode 4: Boiling Point (May 13, 2015) Steve Carl says that he felt disconnected in the fight, something that "never happened before." Dan Lambert notes that Carl was the last guy he expected to hear that from. Conan Silveira tries to instigate motivation in the fighters and Steve Montgomery links his motivation and fighting spirit to that, citing that he is unafraid of losing, and that it all adds up to his own "fire." The coaches believe that is the right attitude for the team. Later, Montgomery is picked to fight next. Glenn Robinson and the rest of Blackzilians' coaching staff visit their fighters at the house. They speculate on Nathan Coy being their possible foe and Jorge Santiago believes that Carrington Banks would be a good choice to face him, something that Robinson is unsure about. Despite that, they all reach consensus on picking Banks for the fight, even though he has less experience than most fighters and has not fought in a while. The calmness in the house is suddenly broken by a scream asking for help on the second floor. It turns out that Montgomery is having a seizure, which scares all of his teammates while they try to help him. Emergency is called and they transfer him to a hospital for better evaluation. Lambert and Silveira try to figure out what to do in case Montgomery is not able to fight. They believe their opponent is either Banks or Jason Jackson. They speculate on whether picking Nathan Coy or Sabah Homasi, ultimately picking the latter. Homasi comments that besides fighting, he is also an "entertainer for women." Montgomery comes back from the hospital accompanied by Lambert. He comments that his seizure was caused by drinking too much water without ingesting any electrolytes with it. Despite having no sequelae, he is forced to leave the competition. He notes that he is more disappointed on what he has done to his team than what he did to himself. White then promises him a shot in the UFC if he stays healthy. Carrington Banks defeated Sabah Homasi via decision after three rounds. Homasi and his coaches are all shocked at the result. Lambert notes that while he was disappointed with some of the previous performances, that was not the case of Homasi.

Episode 5: Battle Wounds (May 20, 2015) Hayder Hassan defeated Andrews Nakahara via TKO (punches) in the first round at 48 seconds. This earns ATT their first win and 50 points, as they have now gained home gym advantage.

Episode 6: Fight Through the Pain (May 27, 2015) Jason Jackson defeated Marcelo Alfaya via majority decision (19–19, 20–18, 20–18) after two rounds. Dan Lambert and the ATT coaching staff express frustration with Alfaya, especially due to his major experience. Lambert says that after the fight, Alfaya told him he was saving energy in the first round. That statement made Lambert wish it was said before the fight, as they would have kept him from fighting next. Dana White reveals another change to the season. On the next episode, both ATT and the Blackzilians will have the opportunity to drop two fighters from the team and substitute two alternates.

Episode 7: Eyes on the Prize (June 3, 2015) The ATT coaches are still disappointed at their fighters. Conan Silveira urges them to seize the opportunity and perform better. He believes that they are wasting a great chance with poor performances. He also tells them to listen more to the coaches. Vicente Luque defeated Nathan Coy via submission (anaconda choke) at 2:26 in the third round. Coy was tearful and dejected about the loss, as the Blackzilians now lead 200 to 50 points and retain home gym advantage.

Episode 8: Lightning Strikes Twice (June 10, 2015) Hayder Hassan defeated Felipe Portela via majority decision (20–18, 19–19, 20–18) after two rounds. With the win, Hassan earns ATT a significant 50 points in the competition and takes home gym advantage for the next fight. The Blackzilians still lead 200 points to 100, but with the next four fights rewarding 100 points each, there is potential for ATT to make a comeback and possibly even win.

Episode 9: No Guts, No Glory (June 17, 2015) Kamarudeen Usman defeated Steve Carl via unanimous decision (20–18, 20–18, 20–18) after two rounds.