NEW YORK -- Throughout the buildup to UFC 217, Rose Namajunas rendered useless the attempts of strawweight champion Joanna Jedrzejczyk's at mental warfare.

Namajunas went on to prove she had just as many answers Saturday for anything Jedrzejczyk had to offer physically.

In a stunning and dominant upset, Namajunas needed just over three minutes to halt the title reign and growing legend of Jedrzejczyk, one victory short of tying Ronda Rousey's UFC women's record of six title defenses.

Namajunas proved unfazed by the moment as she landed the bigger strikes throughout in a first-round stoppage at Madison Square Garden.

How shocking was Namajunas' finish and the stone-cold manner in which she delivered it? She made the reigning champion Jedrzejczyk -- on the short list of greatest female fighters in UFC history -- tap out due to strikes.

Nearly speechless after the victory, with the arena buzzing from the finish, the mild-mannered Namajunas (7-3) could only tell announcer Joe Rogan, "It feels like a movie right now."

Namajunas, 25, entered the fight with a decided advantage on the ground over the champion due to her unique and dangerous submission game. But she dominated Jedrzejczyk on the feet from the opening horn.

Jedrzejczyk (14-1) was dropped by an overhand right early and was repeatedly beaten to the punch from distance. Namajunas later dropped her for good with a looping left hook and instantly followed with a knee to the head and flush right hand to the face on the ground.

Referee John McCarthy waved it off at 3:03 of the opening round.

Namajunas completed a stunning turnaround from her UFC debut in 2014 when she was dominated in a third-round submission loss to Carla Esparza in the inaugural women's strawweight title bout.

Each attempt from Jedrzejczyk, 31, to get inside the head of Namajunas during the promotion -- from news conferences to staredowns at the weigh in -- proved unsuccessful.

"There is so much crap going on in the media and news, and I just want to try and use my gift of mixed martial arts to make the world a better place," Namajunas said. "This is extra. Let's just give each other hugs. When we fight, this is entertainment. Afterwards, it's nothing."

Asked to sum up how she was able to take Jedrzejczyk out, Namajunas shared the mantra she kept repeating to herself on the walk to the cage.

"Confidence, conditioning, compusre, content, I'm the champion," Namajunas said. "That's what I was saying the whole time."