A man accused of raping a woman as she walked through the Adelaide Parklands late at night has told his District Court trial he was trying to "defuse the situation" and only grabbed the front of her pants to "stabilise himself".

Benjamin Joshua Heldon, 45, has pleaded not guilty to two charges of rape over the alleged attack in Victoria Park in Adelaide's CBD in December 2013.

He took to the stand on Thursday, telling the jury he was staying at a backpackers' hostel in the city that night and was out walking when he saw the woman ahead of him on a lit path in Victoria Park.

He told the court he said "hey" as he approached her to which she responded "oh shit".

"When she said 'oh shit', I felt a little bit like, I could see she was a bit concerned … the way she held her bag I thought, my first thought was, 'Does she think I'm trying to steal her bag?'" he said.

"I felt sort of accused, or let's say, that was like a false assumption, an accusation."

Mr Heldon said the woman started moving away from him and he reached forward to touch her on the shoulder "to defuse the situation".

"I felt her collapse underneath my hand and as I accelerated to reach forward and touch her shoulder, which I felt was to make contact and clarify and that it was actually okay … she became [a] rag doll," he said.

"With my momentum, I came over the top of her or crashed onto her."

The court heard after the first scuffle they both managed to get onto their feet and the woman started to move away again.

"She had her back to me as she was running away, or stepping away," Mr Heldon said.

He said he reached for her for a second time because he still wanted to resolve the situation.

"I still had in my mind feeling like she thinks I'm trying to steal her bag," he said.

"I wanted to do what I originally felt I was doing to bring her awareness to that she was okay."

A dreadlock found by police in Victoria Park. ( Supplied: SA Courts )

According to the prosecution, Mr Heldon put his hands down the woman's pants and raped her.

During his testimony, he admitted that he had hold of her around the front of her pants.

"This is the mechanism I used to stop myself from falling back," Mr Heldon said.

The court previously heard the woman fought her attacker off by punching him in the face, gouging his eyes and kicking him off her body.

In doing so, she pulled a long dreadlock from the attacker's head that contained DNA which was matched to Mr Heldon in 2016.

"I was kicked off while she held my hair … I was thrown back and hit the ground," Mr Heldon told the jury.

When questioned whether he touched the woman's genitals, he said he had no recollection of his hand being down her pants.

"I had no intention and I don't know if I did, but I didn't have any intention," he said.

The trial continues.