Australia can boast the fastest qualifiers into the 200 metre finals at the world junior athletics championships in Lima, while South Australian pole vaulter Tryphena Hewett claimed a break-through bronze.

Gout Gout ( 21.07 seconds) and Olympic semi-finalist Torrie Lewis (23.14) won their 200m semi-finals in scintillating fashion, setting the quickest times of the day while fellow Australian Jessica Milat also took out her qualifier into the medal race.

"I took the bend how I wanted it and then I was able to look at the camera and then slow down a bit because I could see I was a little bit in front," said Lewis, with Victorian Zach Della Rocca becoming the fourth Australian in the U20 finals.

Inspired by Olympic champion Nina Kennedy, Hewett clinched Australia's fourth medal after overcoming a shaky start.

Requiring all three attempts at her opening height of 3.95m, Hewett composed herself during the competition to clear 4.05m and then 4.15m to land global bronze.

"After the first two fouls, I thought I was going to no-height and I thought if I could just make a height I would be happy," the 18-year-old said.

"After that I started to get into a rhythm and slowly found a bit of a groove even though my poles were all over the place.

"I was having a shocking month of training before the Olympics and I didn't even know if I could get my full run working here, but I watched Nina (Kennedy) do her thing and this motivation just clicked.

"Since then I have been taking off in training, wanting to jump, feeling that confidence she brought by winning that medal."

As well as the 200m trio, Olympians Peyton Craig and Claudia Hollingsworth also bolted to victories in their respective 800m semi-finals.

Queensland 17-year-old Terrell Thorne placed seventh in the 400m while fresh off a gold medal in the long jump, Delta Amidzovski set a career-best time of 13.22 in the 100m hurdles en route to qualifying for the final.