Harris, who turns 19 in April, began his all-or-nothing campaign on Thursday in the under-20s decathlon event in Brisbane - the only chance he has of world youth qualification after an almost three-month layoff through injury.

The NSW under-20s champion has been recovering from an ankle injury after being diagnosed with bursitis (swelling and pain) in December and, after learning that the Brisbane championships were the only shot he had left of world qualification, has left nothing in the tank in trying to get back to full strength over the past three weeks.

Harris said he had adopted a “throw all caution to the wind” approach to training.

“If my ankle blows up it blows up,” Harris said.

Harris said it was his only shot at qualification this year and it would be really nice to make it.

“If I miss out then there’s the World Uni Games next year, the Commonwealth Games the year after the Olympics two years after that.”

Harris kicked off his Brisbane campaign on Thursday and will continue today.