Also in the mix at this World Athletics Continental Tour Gold meeting will be Bahamian world champion Steven Gardiner, for whom this will be a first meeting with Norman.

The 28-year-old South African, who clocked 43.03sec in winning the Rio 2016 title from the outside lane, was out of action for more than a year after seriously injuring his knee while playing in a charity rugby match in October 2017 but has since returned to competition as he targets the defence of his Olympic title.

Norman, 23, moved to joint fourth on the all-time list in 2019 when he ran 43.45, and Gardiner’s winning time of 43.48 in Doha at the 2019 World Championships means he is just one place further back.

The American has already shown convincing form this season, improving his season’s best with every race and winning at the recent United States Olympic trials in Eugene, Oregon in 44.07.

Gardiner, 25, has run 44.52 this season, and Van Niekerk recently clocked 44.56.

Amid all the uproar over the one-month ban for a positive marijuana test that will preclude the winner of the women’s 100 metres at the US Olympic, Sha'Carri Richardson, from contesting the individual event at the Games, the one woman who has run faster than her this season - Jamaica’s multiple world and Olympic 100m champion Shelly-Ann Fraser-Pryce - will be in action in Hungary.

The 34-year-old, who earlier this year set a Jamaican record of 10.63 to move to second on the world all-time list behind the 1988 record of 10.49 set by the late Florence Joyner-Griffith of the US, will take on a field including American 200m champion Gabby Thomas.

Like Fraser-Pryce, Thomas recently moved up to second on the all-time list in her specialist distance after winning the US trials in 21.61sec - bettered only by Griffith-Joyner's winning time of 21.34 at the Seoul 1988 Olympics.

Jamaica’s Rio 2016 100m and 200m champion Elaine Thompson-Herah, Nigeria’s Blessing Okagbare and 2017 world silver medallist Marie-Josée Ta Lou of the Ivory Coast are also in a stellar field.

Meanwhile another world champion is planning to use the latest World Athletics Continental Tour Gold meeting as a vital warm-up for Tokyo - 110m hurdles king Grant Holloway, who chased and then set a world indoor 60m hurdles record of 7.29 earlier this year.

Holloway is in superb form, having clocked 12.81 - just 0.01sec off the world record set in 2012 by his compatriot Aries Merritt - in the Olympic trials' semi-finals.

The race will also be a key marker for Russia's 2015 world champion Sergey Shubenkov, cleared last month by a disciplinary panel of any wrongdoing after an adverse finding reported in December in what was described as "a genuinely exceptional case".

Spain’s Rio 2016 silver medallist Orlando Ortega is also in the field.

But the 400m hurdles might yet be the story of the day given the re-run in the women’s race of yesterday's Diamond League meeting in Stockholm between 21-year-old Dutch athlete Femke Bol and Shamier Little of the US.

In the Swedish capital they both set huge personal bests, with Bol, winner in 52.37, moving up to fourth on the all-time list and Little, whose stumble at the US Olympic trials cost her the third qualifying place for Tokyo 2020, taking fifth place with 52.39.

In the women’s 200m, the Olympic 400m champion Shaunae Miller-Uibo, who said earlier in the year that she would contest only the shorter sprint in Tokyo but has recently hinted that she may yet seek a 200m-400m double, will take on Jamaican Olympic 400m bronze medallist Shericka Jackson.

Two-time world champion Dafne Schippers of The Netherlands and world bronze medallist Mujinga Kambundji of Switzerland are also in the 200m field.

Tomorrow’s field events were prefaced today by the men's and women's hammer throw, where the respective winners at the last Gold meeting in Bydgoszcz last week, Poland's double Olympic champion and world record-holder Anita Wlodarczyk and four-time world champion Pawel Fajdek were back in the circle.

Wlodarczyk won with 74.76 metres, just seven centimetres ahead of France’s European silver medallist Alexandra Tavernier.

Fajdek had a less successful day, having to settle for third with 78.78m as Ukraine’s Mykhaylo Kokhan won with 80.78m, the fourth best thrown this season,  and fellow Pole Wojciech Nowicki, the Rio 2016 bronze medallist and European silver medallist, was second with 80.58m.

Sweden’s world discus champion Daniel Ståhl will seek to maintain his winning run against a field including the two men who preceded him as world champion - Andrius Gudžius of Lithuania and Piotr Malachowski of Poland.

The men’s triple jump will bring together two 18-metre performers in the form of world indoor record-holder Hugues Fabrice Zango of Burkina Faso and multiple world medallist Pedro Pichardo of Portugal.