BJ Penn and Nate Marquardt appear to be at each others throats with their war of words on their twitter accounts.

"I'll show up to your gym to fight if you do a drug test every week for 3 months. Winner keeps the video. Lmk (:" Penn wrote on his twitter.

"How about I give u my most recent and another one now showing that it's low and I still mop the floor with your midget head?" Marquardt replied on his twitter.

"What a Joke! 1 drug test? lol.. You should be tested every week for 3 months... and then we'll fight. ... I have no doubt I will beat you if you come in natural like i have been doing my entire career." Penn tweeted.

The feud stems from Marquardt getting released and banished from the UFC due to his involvement with testosterone replacement therapy just a day before he was set to headline UFC on Versus 4. The ensuing fallout had many fighters launching verbal attacks criticizing Marquardt for his actions. Among them was Penn who declared through his twitter that the "PED cancer" needs to be removed from MMA and also called Marquardt a cheater, among other derogatory terms.

Their feud would likely be restricted to the web as they trade insults instead of punches. An actual fight between them is highly unlikely as Penn is signed with the UFC and Marquardt's future in MMA still remains a mystery.