Teenage shot put sensation Jacko Gill should be a double world champion by the end of this week - if he overcomes one of his first big setbacks.

On Thursday, the 16-year-old will attempt to add the world youth (under-18) title to the world junior (under-20) championship he won in Moncton, Canada a year ago.

Now being labelled New Zealand's athletics phenomenon in the United States, Gill is in Lille for what should be a certain win in the world youth championships in this northern French city.

He holds the world record in the under-18 age division at 23.86m, set at the New Zealand Secondary Schools Championships last December. His next closest competition in France is a Ukrainian who has recorded 20.60m this year.

But Gill is not quite as confident of a runaway win as he was two months ago. Back then, he astounded the athletics world when he put the senior (Olympic weight) shot 20.01m at a meeting on Auckland's North Shore.

This broke the long-standing New Zealand record of 19.80m set by four-time Olympian Les Mills 44 years earlier.

On the fourth of his six efforts in that competition, however, he badly injured the middle finger of his right throwing hand.

"The finger bent back with the force of the shot as I released it and seriously strained the ligaments and tendons of the finger," Gill explains. "I've had a bone scan on it to check if there are any broken bones. It's okay in that respect but it's been troubling me quite a bit in training - very painful. It's coming right now, however, and I should get through the competition without too many problems."

Gill was hoping to break his world record in Lille and had his sights on raising the world record to over 25m. But he will now be content with the world championship gold and go after the 25m mark later this year.

He has also been invited to compete in the Diamond League meeting in Stockholm later this month, where he would come up against the world's best senior throwers.

"I may still do this but it depends on how the injured finger comes through the world champs," he says. "If it's not 100 per cent, I may have to give it a miss, which would be a pity. But I wouldn't want to go into a competition of that magnitude and not perform up to my best.

"There is another competition for the world's top junior and youth athletes on the same day's programme and I may opt for that."

At the world junior championships last year, Gill (then 15 years, 7 months) became the youngest competitor in the history of the under-20 championships to win gold. The previous youngest was Usain Bolt.

The Jamaican sprint superstar has since won Olympic gold over 100m and 200m in Beijing in 2008 and a world championship 100m-200m double in Berlin in 2009, with world records in both events.