Australia’s fastest man Lachlan Kennedy has been forced to pull out of this year’s world championships due to a back injury.

It’s a shattering blow for the 21-year-old, who this year became the first Australian to run a legal sub-10 since Patrick Johnson in 2003.

Kennedy has been managing the back issue since June, but the situation hasn’t improved.

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He vowed to return stronger than ever with next year’s Commonwealth Games in Glasgow the next big event on his calendar.

“It’s with a heavy heart I have to announce that I will not be competing at this year’s world championships in Tokyo due to a progressing injury,” he wrote on Instagram.

“Grateful for the year and the support I’ve received, I wouldn’t change a thing. I’ll use this time to heal, grow and comeback stronger than ever.”

Kennedy has only run once since breaking 10 seconds in June with a 10.07 effort at the Diamond League meet in Oregon on July 5.

“Lachie was never going to go over to Tokyo just to pick up a tracksuit,” said Kennedy’s manager Nic Bideau.

“He’s shown he can compete with the best this year with the 60m silver medal at the world indoors.

“He’s got a very big three years coming up leading into the Los Angeles Olympics and we were never going to take any risks.”

The news came on the same day dual Olympic walking medallist Jemima Montag also had to withdraw from the world championships, which begins September 13, due to hamstring surgery.

In June this year, Kennedy ran a blistering 9.98s at the Kip Keino Classic in Nairobi, Kenya to join Johnson in the history books.

Kennedy leapt to celebrate the time but just as impressive was nabbing the win over the likes of Paris Olympics 4x100m relay silver medallists Bayanda Walaza and Shaun Maswanganyi, and 2022 Commonwealth Games 100m gold medallist Ferdinand Omanyala.

The 21-year-old had been locked in a friendly rivalry with Gout Gout and Rohan Browning over the summer as they all chased the magical 10-second mark.

Gout and Browning had both broken 10 seconds on home soil, but they didn’t official count due to illegal tailwinds.

Gout also clocked 9.94s over the weekend at a school meet, but it was hand-timed and not recognised officially.

Australia’s final team for Tokyo will be announced next week.