Watch: Amanda Nunes vs. Ronda Rousey Knockout Video

December 31 marks the fourth anniversary of Amanda Nunes versus Ronda Rousey, one of the most impressive fights in the UFC women's history. The bout was the last performance from Rousey with the UFC and as an MMA fighter.

The fight with Rousey was Nunes' first UFC women's bantamweight championship defense after she captured the belt from Miesha Tate. Rousey was the division's reigning unbeaten champion until she was dethroned by Holly Holm. Rousey decided to retire after not recovering her title.

Gone in 48 seconds! Amanda Nunes is back and last time out she destroyed Ronda Rousey... 😮😮😮#UFC215 pic.twitter.com/z84JpCUsTu

— UFC on BT Sport (@btsportufc) September 9, 2017

Amanda Nunes started the bout as aggressive as ever. She went straight to Ronda Rousey with high punches. By completely controlling the center of the octagon, Nunes did not leave space for a reaction from Rousey, the former titleholder.

After only twelve seconds of battle, Rousey absorbed a straight punch to the face that stunned her. It was clear from that moment on that Nunes would successfully keep the belt for herself.

Even with her constant attempts to clinch with Nunes and bring the fight to the ground, Rousey continued to receive violent blows that started to erode her agility and reaction time. Within thirty seconds, Ronda Rousey was struggling to stay on her feet. Nunes remained in unbelievable form and distributed punches to her opponent's face without mercy.

In what was one of her most impressive UFC performances to date, Amanda Nunes forced referee Herb Dean to intervene and cease Ronda Rousey's misery after only 48 seconds.

After Ronda Rousey, Amanda Nunes also beat Cris Cyborg

Almost exactly two years after beating Ronda Rousey, UFC women's double-champion Amanda Nunes etched her name in the promotion's history books by defeating Cris Cyborg for the UFC women's featherweight title.

Amanda Nunes stopped Ronda Rousey in 48 seconds...Amanda Nunes stopped Cyborg in 51 seconds...Two legends of women's MMA gone in under a minute 🤯The 🐐 returns this Saturday at #UFC250! pic.twitter.com/82CXJ90zHL

— UFC on BT Sport (@btsportufc) June 5, 2020

With the win over Cyborg, Nunes became the first woman in the UFC's history to capture UFC titles in two weight classes.

What makes Nunes' accomplishment even more impressive is that it was the first time Cyborg lost an MMA bout since her professional debut back in 2005. Cyborg would only register one more performance in the UFC before joining Bellator.

Nunes maintained both of her titles in the UFC women's bantamweight and featherweight divisions. She became the first fighter in the promotion's history to successfully defend two titles simultaneously.

Amanda Nunes' next fight will happen on March 6 in UFC 259, with the venue yet to be announced. She will defend her UFC women's featherweight title against contender Megan Anderson.

Anderson is a former interim Invicta FC featherweight champion. She joined the UFC in 2018. Anderson has won three of her five appearances inside the octagon.