By TMZ Sports

The woman who claims she was attacked by former world champion Sergey Kovalev has now filed a lawsuit against the Russian fighter ... claiming the 35-year-old also attacked her dog.

It's all in court docs obtained by TMZ ... Jamie Frontz (who has identified herself publicly) claims she met Sergey at the grand opening of a boxing gym in Big Bear, CA back in June.

Frontz -- a model and actress -- claims Sergey and a friend followed her home from the party and Kovalev aggressively tried to have sex with her.

"At one point, Kovalev pinned Jamie to the couch, leaning over her with his hands on either side of her shoulders, such that she could not move away."

Jamie claims her dog sensed the danger and tried to intervene -- but Kovalev shoved the dog away and then kicked it in the chest.

While tending to her dog, Jamie claims, "Kovalev turned to [her] and punched her with full force directly in the face one time with a closed fist."

In her suit, Jamie claims Sergey fled the scene -- so, she called the cops.

TMZ broke the story ... cops tracked down Kovalev and arrested him. He's been charged with felony assault and faces up to 4 years in prison. Kovalev has pleaded not guilty.

In her suit, Jamie claims she went to the emergency room where she was treated for a broken nose, head injuries and a concussion. She also claims to have suffered severe back and neck injuries.

The next morning, Jamie claims she saw Kovalev crawl out of the bushes near her cabin, and he yelled her name -- so, she called 911 and later got a restraining order against him.

Jamie is suing for more than $3 million in damages.

We reached out to Kovalev for comment -- so far, no word back.

Sergey is due back in court in March to face the criminal charge. He's also set to fight WBO champion Eleider Alvarez this Saturday, in a rematch of an August bout that he shockingly lost by knockout.

Frontz took to social media, and took aim at Kovalev - who denies her claims.

"I hear that he is denying on his social media that he punched me in the face. I’m curious as to how he explains the fact that I suddenly wound up with a shattered nose, an open head wound, a concussion and two spinal injuries when he was standing 3 feet away from me in the living room of my own cabin (infuriated because I wouldn’t have sex with him, so much so that he had just viciously kicked my dog Annie)," Frontz stated.

"And there’s an eyewitness who saw the whole thing. Nice try, Krusher. Fortunately, he’s facing felony assault charges and I’m also suing him for $8 million, so one way or the other I suspect the truth will come out. Sadly, I know all to well what its like to get punched in the face by Kovalev, only when he hit me he wasn’t wearing gloves."