Ronda Rousey was able to quickly and impressively defend her Strikeforce title last night with an armbar submission in only 54 seconds. Sarah Kaufman came into the fight as a considerable underdog, but I don't know that anyone expected it to be quite that easy for the champion.

The win was Rousey's sixth career victory, all by armbar. The most incredible thing is that, at 54 seconds, this was the second longest fight of Rousey's career.

Here are the ESPN video highlights for the bout:

Here's how the action was called during the Bloody Elbow live blog:

Ronda Rousey vs. Sarah Kaufman - Round 1 - Rousey coming forward throwing and she gets inside and gets a takedown and has mount. Rousey looking for the armbar already. Kaufman defending well so far but Rousey staying on the arm and there's the tap. Good lord, she is incredible. Ronda Rousey wins by submission (armbar), round 1.

SBN coverage of Strikeforce: Rousey vs. Kaufman