"If he had a weapon I didn't know, I just started punching, screaming, fighting and swearing."
Roudon was about three minutes' walk from home after having new false acrylic nails applied because she planned to attend singer Nicki Minaj's concert last night.
Roudon's friend had dropped her to the 7.34pm train from Avondale. The man was in the same carriage, but she took little notice.
When she got off the train it was still daylight. She hadn't noticed he had got off too.
When she thought she heard someone walking behind her, she switched into high alert and walked briskly down the secluded path that she walks down almost every day, leading from the Sunnyvale train station to Newham Place.
"I kept looking left and right using my peripherals because I had that feeling of being stalked. I kept walking."
When the person didn't pass her, she stopped, bent down and pretended to tie her shoe. But he still didn't pass. She turned around to see what was happening and he grabbed her.
"I dropped my bag and just started fighting him. I scratched his face, punched him. I was swearing at him, yelling and I kicked him, twice. A good kick in his groin."
They were face-to-face and he was trying to hold her. "I just let loose. I went to kick him again and he grabbed my leg to try to get me off balance but somehow I stayed on my feet and I kept hitting him and yelling. That's when I looked at him and he looked shocked. He just punched me in the face and took off back the way we had come."
Roudon was helped home by two passersby.
She didn't feel up to going to Minaj's concert last night and was reviewing how she gets to and from the train station.
Police had to clip her nails as they contained valuable DNA evidence, namely skin from the man's face.
Waitakere Detective Sergeant Peter Litherland praised Roudon's "gutsy display".
The man is described as a skinny Pacific Islander or Indian, aged in his late 20s or early 30s, with short black hair. He would now have scratch marks visible on his face.
He was wearing a long-sleeved grey sweatshirt, black full-length pants and black shoes.
Police would like to hear from anyone who saw the man on the train or who knows who he is.
"The male will have difficulty concealing the injuries to his face."
If you can help, phone Waitakere police on (09) 839 0627 or Crime Stoppers on 0800 555 111.