This lady ain't playing.

Strikeforce bantamweight champion "Rowdy" Ronda Rousey held on to her title on Saturday night when she defeated Sarah Kaufman by armbar just 54 seconds into round one. Following her dominance over Miesha Tate in their March bout, many critics said she would have to prove herself against Kaufman to be considered number one. And she promtply shut all the naysayers up.

Rousey, who won a bronze medal in Judo at the 2008 Olympics in Beijing, now has a 6-0 record, with all her victories coming by way of submission, namely, her now-signature armbar in the first round. (Check out her armbar win over Tate here).

The champion immediately made it clear that she wants to fight former featherweight (145-lb.) champion Cris "Cyborg" Santos, who lost her belt after testing positive for stanozolol last year.

"First of all, I need to send a challenge to Miss Cyroid out there," the oustpoken fighter told Jimmy Lennon Jr. "People want to see you have the first fair fight of your life. I am the champ now, the champ doesn't go to you, you go to the champ. Come down to 135 and let's settle this."

With the Brazilian still serving her doping ban, it will be interesting to see who Rousey fights next. With her looks (check out her gallery here), her take-no-crap character and her undoubted talent, this champion is putting women's MMA on the map in a big way. More power to you, Rhonda!

Check out the fight and the full post-fight interview here: