Ostrava - Wayde van Niekerk had promised to get "ridiculous" and the South African tyro hailed as Usain Bolt's likely successor did just that when sprinting to a world record in the rarely-run 300m on Wednesday.

The 24-year-old raced home at the Golden Spike meet at the Mestsky Stadium in the northeastern Czech city of Ostrava in an outstanding 30.81 seconds.

The previous world record of 30.85sec was set at altitude in Pretoria in 2000 by American Michael Johnson.

It was the second time the 24-year-old South African has usurped Johnson, having broken his 17-year-old 400m world record when racing to victory at last year's Rio Olympics.

Van Niekerk's time also shattered the meet record of 30.97sec -- previously the second fastest time every run -- set by Jamaican sprint star Bolt in 2010.

"I'm so pleased and grateful for this big achievement," said Van Niekerk, whose first professional appearance on the IAAF circuit was over 400m at Ostrava.

"Thanks to all the people of Ostrava for this wonderful meeting. I'm honoured to be a small part of history.

"I have to rest a little but after that I hope I can continue to make babysteps to be better day by day."

Running in lane five, Van Niekerk enjoyed a scintillating start that saw him catapult down the back stretch and pass Isaac Makwala of Botswana after the first 80 metres.

Negotiating the bend with aplomb, the South African shot into the home straight well in the lead.

As he seemed to pull up slightly, Makwala pushed but a final spurt saw Van Niekerk ease past Johnson's previous best.

The result is another feather in the cap for the world and Olympic 400m champion, who this year has set a leading mark of 19.84sec in the 200m and a personal record of 9.94sec in the 100m.

Van Niekerk is also the first athlete to break 10sec for the 100m, 20sec for the 200m and 44sec for the 400m, and it is little wonder Bolt himself tips the South African as his most likely successor when he hangs up his spikes come the season's end.

Van Niekerk will aim to double up in the August 4-13 World Athletics Championships, in the 200 and 400m, meaning a packed racing programme of six back-to-back days of competition.

"There's still a lot of work to be done," he insisted.

"I have faith in my coach, I just go out and try to execute to the best of my ability.

"This world record is a blessing. It's a massive confidence booster," he acknowledged, dubbing it an "honour" to twice better Johnson.