The Zawisza Stadium in Bygoszcz witnessed a world under-20 400m record of 48.54sec tonight from Namibia's Christine Mboma that put her seventh on the all-time list ©YouTube/World Athletics

Eighteen-year-old Namibian Christine Mboma produced a startling performance at tonight’s Irena Szewińska Memorial meeting in the Polish city of Bydgoszcz as she won the women’s 400 metres by half the length of the finishing straight in 48.54sec - a world under-20 record and the fastest run so far this year.

It marked another dizzying step up for Mboma, who set a personal best of 50.97 on March 27 this year and trimmed it with a Namibian record and unofficial world under-20 record of 49.24 on April 11, breaking the mark of 49.42 set in 1991 by East Germany’s Gritt Breuer.

A week later she lowered her best to 49.22, and her latest effort takes her above Rio 2016 champion Shaunae Miller-Uibo, who clocked 49.08 in April, in the 2021 world rankings.

Mboma’s time establishes her in seventh place on the all-time women’s 400m list and provides the women’s 400m with a different talking point to the news that broke shortly before the meeting began that Salwa Eid Naser of Bahrain, who went third on the all-time list in winning the 2019 world title in 48.14, had been banned for two years for missing three anti-doping tests in a 12-month period.

For Miller-Uibo, who took silver at the Doha World Championships behind Naser, no sooner has one major rival disappeared off her radar for Tokyo than she has a new contender front and centre.

Poland’s European champion Justyna Święty-Ersetic was a distant second in 51.91sec.

Elsewhere in the latest World Athletics Continental Tour Gold meeting at the Zawisza Stadium, home world champion hammer throwers Anita Wlodarczyk and Pawel Fajdek produced powerful winning statements of intent with the Olympics on the horizon.

Wlodarczyk, the 35-year-old double Olympic champion and four time a world gold medallist, who has been recovering her form after surgery, indicated her readiness to do battle in defence of her Rio 2016 title with a throw of 77.93 metres - her best since winning the European title in 2018.

All six of Wlodarczyk’s throws were comfortably in excess of her previous season’s best of 74.06m.

Fellow Pole Malwina Kopron, the 2017 world bronze medallist who had beaten her at the weekend’s National Championships, was second with 73.69m ahead of France’s European silver medallist Alexandra Tavernier, whose best was 71.89m.

Fajdek, a four-time world champion but so far without a single Olympic medal, produced a meeting record of 82.77m, just 0.21m short of his own 2021 world-leading mark and 0.06m further than Rudy Winkler’s national record set at the recent United States Olympic trials.

Poland’s Olympic bronze and European gold medallist Wojciech Nowicki was second with 80.00m.

But Poland’s field event feelgood factor dipped when it came to the men’s shot put, where European champion Michal Haratyk could only manage sixth place with 20.42m in a competition won by 2017 world champion Tom Walsh of New Zealand with a best of 21.46m.

Serbia’s Armin Sinančević was second on 21.16m, and Nigeria’s aptly-named Chuk Enekwechi third on 21.11m.

There was home disappointment too in the men’s 800 metres, where 31-year-old Adam Kszczot, a triple European champion and former world indoor champion, failed once again to find the spark that has been missing from his running this season.

Kszczot was fifth in 1min 47.97sec in a race won in 1:45.76 by Kenya’s Cornelius Tuwei, who won in Turku at the start of the month, with Britain’s Jamie Webb second in 1:46.04.

A top-class men’s pole vault was won by Chris Nilsen of the US with 5.92 metres, just a centimetre below his personal best.

Ernest Obiena of The Philippines set a personal best of 5.87m in second place, with Poland’s 2017 world silver medallist Piotr Lisek third on 5.82m.

There was an Ethiopian one-two in the women's 800 metres as Worknesh Mesele beat Diribe Welteji in a meeting record of 1min 59.39sec.

Spain’s Rio 2016 silver medallist Orlando Ortega won the men’s 110m hurdles final in 13.33sec from Poland’s Damian Czykier, who clocked 13.60.

The men’s 3,000 metres steeplechase was won by Ethiopia's Abraham Sime in 8min 21.41sec from Uganda’s Albert Chemutai, who clocked 8:23.65.

European 100m hurdles champion Elvira Herman of Belarus won in 13.15sec.

Michelle-Lee Ahye of Trinidad and Tobago won the women’s 100m in 11.33sec.

Ethiopia’s Tigist Ketema won the women’s 1500 metres in 4min 3.90sec ahead of the 2019 African Games silver medallist Rababe Arafi of Morocco, who clocked 4:05.97, and Kenya’s Mercy Cherono, who finished in a season’s best of 4:08.26.