MMA fighter Jon Koppenhaver, better known as War Machine, pleaded "not guilty" to the charges of attempted murder and sexual assault against his ex-girlfriend Christy Mack whom he allegedly beat up--resulting in severe injuries.

War Machine appeared before a Las Vegas court to face the charges which also include allegations of burglary, kidnapping, coercion and sexual assault, according to Daily Mail.

The MMA fighter was arrested on Aug. 15 in connection to beating Mack about a month ago. In her statement to the police, the porn star claimed that her former beau beat him and threatened to kill her.

Recalling the incidents leading to the assault, Mack told Daily Mail that War Machine arrived unannounced in her Las Vegas home after their recent breakup.

"When he arrived, he found myself and one other fully clothed and unarmed in the house. Without a single word spoken, he began beating my friend; once he was finished, he sent my friend away and turned his attention to me.

"He made me undress and shower in front of him, then dragged me out and beat my face. I have no recollection of how many times I was hit, I just know my injuries that resulted from my beating," she explained. 

She added that the MMA fighter even pushed a knife on different parts of her body threatening to use it to kill her eventually. "I believed I was going to die," she said.

Authorities earlier announced that Mack sustained bruises and fractures on her face and also had a lacerated liver. She is reported to have been recovering after undergoing some surgeries. Her credibility, however, was questioned when she was seen walking the streets of Los Angeles recently.

Appearing before the judge with two security officers escorting him, the MMA fighter said that he fully understood the charges against him and opted to use his original name in the proceedings.

His lawyer, Brandon Sua, told Fox Sports that the public will understand his character.

''He is controversial and people need to understand where to draw that line from his character as War Machine and a person as Jon Koppenhaver, because that's who he is,'' Sua added.

The suspect was ordered held without bail by Las Vegas Justice of the Peace Melanie Andress-Tobiasson. His preliminary hearing is set on Oct. 17.

His legal counsels revealed that they will do everything they can to fight the allegations against War Machine especially the new ones--involving burglary and witness tampering.

Daily Mail said War Machine's lawyers initially claimed that his actions were only ways of defending himself against Mack and her friend Corey Thomas.

Like Mack, Thomas also reportedly had broken bones on his face and was also taken to the hospital for immediate medical attention.