Season 20 of the UFC’s venerable reality series, “The Ultimate Fighter,” was designed to build up the roster of female fighters. The UFC had just entered the women’s game the year before when it introduced Ronda Rousey to the world, and wanted to expand its offering of female fighters.

A number of the fighters had big reputations at the time of the show, including Felice Herrig, Joanne Calderwood (now Wood), Tecia Torres, Carla Esparza and Jessica Penne.

But before filming had begun, Pat Barry, then a UFC heavyweight, kept talking up a fighter that didn’t have the high profile of some of her peers. Watch Rose Namajunas, Barry said to anyone who would listen. She’s the best of these women, he said.

It turns out that though Barry had a conflict of interest — Namajunas was, and is now, his girlfriend — he knew of what he spoke. Namajunas is a two-time strawweight champion and among the five greatest women to ever compete in the UFC at this point.

On Saturday, Namajunas will put her belt on the line against Esparza in the co-main event of UFC 274 at the Footprint Center in Phoenix, a rematch of their title bout at “The Ultimate Fighter Finale” in 2014.

Esparza won that fight by submission in the third round via a rear naked choke, handing Namajunas her second consecutive defeat.

Namajunas is one of the most blunt athletes in the world. She is open about her emotions and concedes she quit against Esparza. She also admits there is pressure on her this time around.

Few athletes are that open, particularly when it comes to their shortcomings.

“For me, it’s a little more challenging when everybody [expects me to win],” Namajunas said. “I don’t mind when people count me out.”

This time around, Namajunas is a solid -225 favorite at BetMGM, coming into the bout 9-2 in her last 11 and having established herself as one of the OGs of the women's game along with Julianna Peña, Amanda Nunes and Valentina Shevchenko.

The growth in Namajunas has been remarkable. She went 3-0 on the show, submitting Randa Markos and Wood with Kimuras and Alex Chambers with a rear naked choke. She met Esparza, who had beaten Angela Hill, Torres and Penne on the show, in the finals.

Confidence has often been an issue for her, but it wasn’t that night. It’s one of the many areas of growth in her game, though.

“Back then, I thought that as long as I show up, I’m good, I’m the best,” she said. “Whereas now, I’ve learned that I have the ability to be the best. And if I do that, that’s usually OK. So far, when I’ve prepared my best and I’ve done my best, nobody can mess with me. I’ve been pretty spot on with that and so what I learned is to keep doing my best and things will usually work out.”

Namajunas has beaten a who’s who of the best women’s talent of the last decade, and often done it in decisive fashion. UFC president Dana White isn’t surprised by what she’s done, because he saw glimpses of what she was capable of doing during the filming of TUF 20.

And he noted that she went out and turned her weaknesses into strengths. That’s usually the sign of a successful athlete.

“She always showed signs of super talent,” White told Yahoo Sports. “She’s worked hard and done what she’s needed to do. Tightened up her stand-up game. I mean, her stand-up game is unbelievable.”

She’s fighting an opponent in Esparza who not only defeated her decisively the last time, but has also improved considerably. She’s won five in a row and was particularly impressive in her last three, wins over Michelle Waterson, Marina Rodriguez and Yan Xiaonan.

White said Esparza, too, has grown more comfortable with her position as one of the elite women in the game.

“Neither one of them are the same fighter that they were when they first squared off,” White said. “It’s almost like Carla, when she went into the [title] fight with Joanna Jedrzejczyk, it almost felt like she felt she didn’t belong there at the time.

“She’s got some time under her belt. She realizes she belongs here now. She’s tough. She’s gritty. She grinds people out and beats them up. This is a fun fight now at this time, with both these girls being so much more mature here in the UFC.”

Namajunas has one secret edge, though: She’s brilliant in rematches. She’s fought two times each against Zhang Weili, Jessica Andrade, Joanna Jedrzejczyk and Tecia Torres. She’s 6-2 overall in those eight bouts, but is 4-0 in the rematches.

So that would suggest she’s a good bet to get past Esparza on Saturday. If Namajunas has learned anything in her time in the UFC, though, it’s not to look ahead.

And so she’s just intent on being the best she can be and letting the chips fall where they may.

“I try to control and make sure I’m on top of everything that is in my power and within my control,” she said. “If I have done that, it’s usually good news but if not, I know there wasn’t anything else I could do. It bothers you more when you go out and don’t perform and know you had more to give. But if you gave it all and did what you could, the results will take care of themselves.”