This season did not feature an elimination round like the two seasons before it, however, the "wild card" selections introduced in season 11 were still featured. The initial cast was 14 fighters rather than the usual 16, 28 or 32 in recent seasons.
On May 12, 2011, midway through the airing of the season, Dana White announced that Brock Lesnar pulled out of the coaches' fight due to the return of diverticulitis, forcing Lesnar to withdraw from the bout.
Dana White welcomed 14 fighters to the UFC training facility and announced that all 14 would automatically get into the house. He also announced the return of the wildcard format.
The coaches for the season were introduced as Brock Lesnar and Junior dos Santos. They then went on to evaluate the fighters.
During the evaluations, Jury got injured and was checked out by a doctor, who said that nothing was broken but still wanted to do an MRI.
Both coaches met in White's office to go through the fighter picks via a coin toss (green for Lesnar, grey for dos Santos). The coin toss was won by Lesnar who chose to pick the first fighter, leaving dos Santos with first choice of matches.
Jury was told that he had a torn ACL and was forced off the show. White promised that he would get a second shot into the UFC after he heals up.
Dos Santos announced that Bailey will face Asrih.
Both fighters speak of their religious backgrounds, as Bailey is the son of a pastor and Asrih is a German-born Muslim.
Shamar Bailey defeated Nordin Asrih by unanimous decision after two rounds.
Episode 2: Suck It Up
Keon Caldwell struggled during an intense Team dos Santos training session and vomited. He told dos Santos that it was hard for him to be away from his family.
Lesnar admitted that he expected to lose the first fight between his sixth pick Nordin Asrih and Team dos Santos' top pick Shamar Bailey.
Caldwell told dos Santos the next day that he wanted to go home. Dos Santos, and later White, encourage to him to keep going. After initially agreeing to continue, Caldwell later changed his mind and left the show.
Dos Santos announced that Torres would face Cope.
Chris Cope defeated Javier Torres via unanimous decision after three rounds.
Episode 3: Chicken Salad
Lesnar's "making chicken salad out of chicken shit" comment confused his team, but he recovered by telling his fighters they became chicken salad once they had made it onto the show, and he also told them to stay motivated.
Dos Santos' wrestling coach Lew Polley ran an intense training session that eventually resulted in Shamar Bailey being cut above the eye.
Lesnar announced that Bentley would face McGillivray.
Chris Cope was seen hanging out with Team dos Santos a lot, making the rest of the green team wonder what his motives were. Bentley seemed especially suspicious and asked Lesnar to talk to Cope, who told him to calm down and fight.
Dissatisfied with Polley's training sessions, dos Santos reminded him that the competition is a team effort, not his own.
Four hours prior to weigh-in, McGillivray weighed 180 lb, so he cut the weight in 45 minutes with Polley and dos Santos in an Epsom salt bath. Both fighters weighed in at 170 lb.
Maurício "Shogun" Rua paid a visit to dos Santos in support of the grey team and to watch the fight cageside.
Lesnar was absent from the fight due to personal reasons.
Ryan McGillivray defeated Len Bentley by majority decision after two rounds.
Episode 4: A Bad Dream
Lesnar returned after leaving before the Bentley-McGillivray fight and congratulated Len Bentley on his efforts. Lesnar showed a commitment to getting wins from his four remaining fighters yet to compete: Tony Ferguson, Clay Harvison, Chuck O'Neil, and Rader.
Lesnar removed Harvison from a training session momentarily for looking distracted and not committed. He also was angry with Rader for the same reasons.
Dos Santos announced that Ramsey Nijem would face Rader.
Lesnar invited Matt Hughes as a guest instructor for wrestling techniques.
Ramsey Nijem defeated Charlie Rader by submission (rear naked choke) at 3:31 of the second round.
Lesnar and O'Neil were visibly upset. Inside the dressing room, Lesnar began to scold the team, prompting Bentley to storm out of the room.
Episode 5: Wow Me
As Lesnar continued to scold his team after Charlie Rader's loss to Ramsey Nijem, Len Bentley came back into the room, and Lesnar questioned his toughness. He said that Chris Cope (the only fighter on the green team to win his bout through four preliminary fights) is the only one that has impressed him so far.
Back at the house, Bentley continued to vent his frustration and showed his dislike of Lesnar.
Dos Santos announced that Bowman would face Harvison.
At a Team dos Santos training session, dos Santos was drilling boxing techniques when Lew Polley took over, leaving dos Santos unhappy with him.
As Harvison trained for his upcoming bout, he was annoyed that Cope was watching him. Harvison said in a confessional he knew "a shady person" when he saw one.
Someone wrote "Chris Cope Double Agent" in the sand in the zen garden. Cope asked his team whether they thought he was a spy or not, and most of the team said they had "suspicions." Later that night, Cope entered the team bedroom and blamed Tony Ferguson for the message in the sand, based on handwriting similarities. Things got heated and everyone was paranoid.
Bowman confessed to a few of his teammates that he wrote the message, saying "it was only meant to be a bit of fun." Ironically, his motive was that he sometimes thought that Cope was hanging around his team to bring information back to Team Lesnar.
Clay Harvison defeated Mick Bowman by unanimous decision after two rounds.
During the fight, Harvison had blocked a switch kick with his hand, breaking his pinky finger with the bone sticking out of the skin. His TUF stint was in jeopardy.
Episode 6: Mean Streak
During a sparring session, Len Bentley collapsed in pain holding his knee. Lesnar was bothered by the injuries his team was sustaining.
Clay Harvison and Bentley were both at the hospital where they found that both their respective injuries were nothing too serious.
Dos Santos discovered that Lew Polley tried to visit the fighters' house on his own which made him feel like Polley was overstepping his boundaries once again. Cigano asked fellow coach Luiz Dorea for advice. Following Dorea's advice, dos Santos decides to send Polley home.
Lesnar announces the match-ups: Tony Ferguson vs. Justin Edwards and Chuck O'Neil vs. Zach Davis.
Tony Ferguson defeated Justin Edwards by KO (upkick) at 3:56 of the first round.
Zach Davis defeated Chuck O'Neil by submission (triangle choke) at 3:20 of the first round.
The wildcard match is decided. Edwards was picked, but was told that he cannot compete due to being suspended by the athletic commission.
The wildcard matches up Torres against O'Neil.
Episode 7: It's Just Good To Win
Len Bentley of Team Lesnar was confused about why he was not chosen for the wildcard match. He confronted White about it but instead, asked for a rematch with McGillivray at the finale.
Cope and Bailey got into a confrontation. Bailey stated that he was annoyed with Cope yelling "woo" and that he wanted to fight him.
Dos Santos defeats Lesnar in the Coaches' Challenge which involved football drills.
After winning, dos Santos gave his share of the cash prize with members of the green team excluding Lesnar himself.
Chuck O'Neil defeated Javier Torres by submission (d'arce choke) at 4:31 in the second round.
The quarter-finals matches are announced:
Clay Harvison vs Ramsey Nijem
Chris Cope vs. Shamar Bailey
Chuck O'Neil vs. Zach Davis
Tony Ferguson vs. Ryan McGillivray
Episode 8: Shut Him Up
Shamar Bailey confided to his teammate about a back injury he had.
UFC middleweight Brian Stann arrived at the gym to give a pep-talk to the fighters.
Ramsey Nijem defeated Clay Harvison by submission (rear-naked choke) at :56 in the first round.
Cope asked his teammate Nordin Asrih for advice on fighting Bailey.
Chris Cope defeated Shamar Bailey by unanimous decision after two rounds.
Episode 9: Then It Turned Ugly
Chuck O'Neil tried to share the $5000 he earned in his finish bonus with his friend Charlie Rader. It is revealed that Rader owes child support and had not seen his child in over a year.
Chuck O'Neil defeated Zach Davis via unanimous decision after two rounds.
Davis returned to the house and reveals that he had suffered torn retinas in both his eyes. He said that the doctors have told him that he could no longer fight and that he would have to retire.
Tony Ferguson defeated Ryan McGillivray by TKO (punches) at :46 in the first round.
The semi-finals matches were announced:
Chris Cope vs. Ramsey Nijem
Tony Ferguson vs. Chuck O'Neil
Both teams joined together to party after the fights. Rader poured alcohol on Ferguson as a joke, but his teammate reacted badly. Both got into a heated confrontation which lead to Ferguson mentioning Rader's problems involving his estranged son.
Members of both teams tried to break-up the fight. Ferguson left to cool off in the pool while the others comforted Rader inside, but when Ferguson came back, he started where he left off.
The argument was finally settled, but both teams were angered and disgusted by Ferguson's actions.
Episode 10: The Biggest Test
Tony Ferguson apologized to his team about his actions, but his team did not believe that his apology was sincere.
Ramsey Nijem defeated Chris Cope by TKO (punches) at 1:49 in the second round.
Tony Ferguson defeated Chuck O'Neil by TKO (punches) at 3:10 in the third round.
Following the conclusion of the episode, Lesnar phoned White to tell him that he had to pull out of his bout with dos Santos at UFC 131. White went on to say that Lesnar would be replaced by Shane Carwin.