Kaitlin Ward, 27, testified she dated Calgary Stampeders running back Joffrey Reynolds for six years before ending their relationship in December 2011 after discovering he had been cheating on her.
She said they were still friends and were trying to determine if they could "salvage" their relationship when she allowed him to stay with her for a couple of days last July after his house went into foreclosure.
Ward said she told Reynolds he had to get out while the two were at a party put on by Stamps receiver Nik Lewis at a bar. She said Reynolds got angry and kicked her in the back of the leg.
When she went home later, she said, he was there waiting for her.
"I was shocked," said Ward. "I went by the front door to shoo him out. That's when he kind of tackled me."
Ward told Judge Brian Stevenson that Reynolds was sitting on top of her.
"He's smothering my mouth and choking me. Shoving his chin into my neck," she said softly. "I was gasping for air at that point."
Ward said Reynolds was yelling at her while he had his hands around her neck.
"He said: 'You're not so tough now that you're alone. What are you going to do?'" she recalled.
Reynolds pulled her to her feet by her hair and then knocked her to the floor again, Ward testified.
"He kind of jumped from behind and put his knee into my back and started choking me again."
She said Reynolds started to calm down when she told him he could stay with her and they went to bed.
But she said she was nervous that night. She texted her friends the next morning that she needed to get out of the house and then left, telling Reynolds she was going to get some makeup to cover the marks on her neck.
Reynolds was charged with assault causing bodily harm, common assault and breaking and entering with intent.
Reynold's lawyer, Randi Collins, questioned the injury to Ward's back. Collins pointed out the running back is five foot 10 inches tall, while Ward is six-foot-five.
She suggested her client was at the condo and falling asleep when Ward arrived home and started yelling at him.
"You confronted him about what you learned about his cheating," said Collins.
"I am going to suggest to you that you went up to him and hit him."
"That would be false," replied Ward.
Collins suggested Ward was out of control.
"I am going to suggest to you he used one hand over your mouth to keep you from yelling and screaming."
Ward's friend took the stand and testified that she witnessed a heated discussion between Reynolds and Ward at the bar.
"She started walking away and he started following her," said Andrea Hogarth. "I started following him."
"He kicked her in the back of the leg. She stumbled and fell down. I stepped in front of him and said, 'What are you doing?'
"He was very aggressive. He was very angry."
Hogarth said she saw the bruises when Ward came to her home the next day.
"She had marks on her neck. They were dark purple on each side of her neck. There was like fingerprints on the one side," said Hogarth as she brushed away tears.
"In the back, between her shoulder blades, there was a bruise there, too."
A police witness testified that Reynold's Cadillac Escalade was found parked illegally, near a six-metre retaining wall near Ward's condo. There were footprints on the hood, which suggested Reynolds may have used it to vault over the wall and gain access.
Investigators, who were given a key by Ward, said Reynolds was found naked in the bedroom and arrested without incident.
The Crown wrapped up its case. The defence intends to call at least one witness Friday morning.
Reynolds is from Texas and played college football at the University of Houston.
He played eight years for the Stampeders and was the franchise's all-time leading rusher with 9,213 yards.
He was named a CFL all-star four times and won a Grey Cup championship with the Stampeders in 2008 before his release in 2012.