Teenage swimmer claims first Aussie gold

Teenage swimming debutante Lakeisha Patterson has claimed Australia's first Paralympic gold in Rio, winning the women's S8 400m freestyle in world record time.

The 17-year-old led from the 100m mark and hit the wall in 4mins 40.33sec, shaving 0.11s off the previous mark held by American Jessica Long, who finished second.

It was a huge triumph for the Queenslander over Long, who is a 12-time gold medallist.

"I knew I had to attack and not let go. I knew she was right behind me," Patterson said.

"She has been my idol growing up and to race alongside her and to get past her is amazing... I felt quite bad. She has achieved so many things and I have come out of nowhere.

"I did not think my first Games would end up like this."

Long, a four-time Paralympian, said she knew it would be a tough race against the rookie.

"Lakeisha did a great job so I am happy to hold on for the silver," she said.

"I had to overcome some injuries to compete, so it is a good result."

Earlier on Thursday (Friday AEST), para-cyclist Sue Powell claimed Australia's first medal by taking out silver in the women's C4 3km individual pursuit.