The 30-year-old woman was struck by a van in the Junction on Wednesday and she remains in hospital in critical condition.
But if it wasn't for Clayton Blackwood, she may have died right there on the street.
He was cycling down Annette Street that afternoon when he saw the woman try to cross the road. The van's driver was attempting to make a left turn when he slammed into her.
"I saw her lying there and she was very seriously injured," he recalls. He dropped his bike and rushed to help her. An ambulance was on its way, but Blackwood knew she might die without immediate help.
Lessons learned from a two-week first aid course came storming back into his mind, and he put his basic knowledge into action. He supported her head and monitored her breathing.
"I had to clear her airway, she was filling up with fluid. I realized she was more than bleeding from her ear," he told CBC News from the site where the dramatic scene unfolded, now marked with memorial flowers.
He credits his first aid training with keeping the woman alive until emergency crews arrived.
"Very glad I had it. You always hope you never have to use it, but when you do..." he said.
Lorainne Deming, who runs first aid training sessions in the GTA, says that classes should be mandatory in Ontario high schools.
"It's something that everybody should know how to do," she said, adding that there are other countries where it is widely taught in schools.
"Maybe one day you're going to need it."
Toronto police continue to investigate the incident. No charges have been laid against the driver.
"I'd really like to see her," said Blackwood. "I hope she's doing well."