Teenage world shot put sensation Jacko Gill is certain he will qualify for the London Olympics when he lines up against the world's best in Sweden in late July.

The 16-year-old from Devonport has stunned athletics with his achievements, including bettering the Olympic qualification mark at North Harbour last Saturday.

He has still to book a place for London however because the Olympic qualifying period, which the IAAF extended by five months for these Games, begins on Sunday.

One throw at the Millennium Centre pipped the 20 metre qualification standard and he was just short with another - an extraordinary achievement for a 16-year-old.

The 96kg Gill, a lightweight compared with most top shot putters, broke the 44-year national record held by Les Mills and became the youngest person to throw more than 20m.

Gill, who left Takapuna Grammar at the end of last year to concentrate on his Olympic bid, received an invitation late on Tuesday night to the DN Galan meeting in Stockholm, the setting for a record 83 world athletics records.

While the Diamond League meeting is held in the city's 1912 Olympic stadium, a unique "Big Shot" shot put competition takes place at the Kungstradgarden (Kings Garden), a tree-lined square in the heart of the city.

Gill was unfazed by having to break the Olympic mark again. He is a quietly spoken young man who prefers action to words but told the Herald he is capable of breaking the 23.12m world record - set in 1990 by American Randy Barnes - at the London Games.

He will compete in New Caledonia next week, but with the 6kg shot instead of the 7.26kg Olympic shot.

"It's wonderful to be invited to Sweden - it is the biggest event on the athletics calendar," said Gill last night.

"That's the next time I'll compete with the senior shot and I should break the qualifying mark by about a metre then.

"I'm not worried at all. It is great being able to break 20 metres already but I'm not in this to only just qualify for the Olympics. I'm planning to [win a] medal in London."

Gill became the youngest male junior world athletics champion last year, usurping sprint superstar Usain Bolt. Olympic Games throwing events are age restricted and Gill qualifies for London by just 11 days.

Leading athletics figures around the world are predicting a remarkable career for Gill.

American track and field coach Dave Wolman told the Herald on Sunday he had never seen anything to match Gill in 35 years of coaching. He believed the young Aucklander will revolutionise the sport.

Athletics New Zealand is seeking an age dispensation so Gill can compete at August's senior world athletics championships in South Korea.

Meanwhile Gill may have created another shot put first in a bizarre training accident at his family's home this week.

A spin exercise gone badly wrong resulted in a 20kg dumbbell going through the windshield and bonnet of a 1956 Buick convertible, one of four antique American cars owned by his father Walter, himself a former national throwing champion.

Jacko Gill joked it might be a $10,000 mistake that would cause him to be grounded.