A world lead, the time is also a new African and South African record, and not even a personal best by LaShawn Merritt in second, of 43.65, could deny the South African gold.

Olympic champion Kiranui James of Grenada was third in 43.78.

Kenya boosted their lead at the top of the medals table by adding two more gold medals to their new tally of six.

Julius Yego won the men’s javelin in a world leading 92.82 metres. It’s Kenya’s first ever throwing medal at a global event.

Then, a famous late surge by Hyvin Jepkemoi saw her claim the women’s 3000m steeplechase, pipping Tunisia’s Habiba Ghribi and Germany’s Gesa Krause, who competed indoors in Athlone in February.

Zuzana Hejnová was relentless as retained her 400m hurdles crown, having almost half-a-second to spare over American pair Shamier Little and Cassandra Tate, in winning with a time of 53.50, another world lead.

Yarisley Silva of Cuba won the women’s pole vault for her first ever global crown, having won Olympic silver in 2012 and world bronze in Moscow two years ago.

Usain Bolt and Justin Gatlin both won their 200m semi-finals, Gatlin marginally the faster – 19.87 seconds compared to the defending champion’s 19.95.

The three Irish athletes in action on Day 5 all exited at the first-round stage, but showed differing emotions to their departures.

Kelly Proper finished marginally outside her season’s best as she bowed out of the 200 metres at the first-round stage.

The Ferrybank AC athlete from Waterford clocked 23.28 seconds in finishing sixth in her heat, four-hundredths away from her best time of 2015.

However, something closer to her personal best of 23.15 was needed in order to get through.

Jeneba Tarmoh of the United States won Proper’s heat in 22.79 as all seven heat winners dipped under 23 seconds, including European champion Dafne Schippers, and despite running in the wrong lane, Veronica Campbell-Brown of Jamaica, who was reprieved for running into an outside lane, thus adding distance.

Proper had made it to Beijing via the IAAF’s new quota system, having consistently recorded times within an ace of the world qualifying time.

However the 27-year-old, who has concentrated on the 200m this season and who scored a famous victory at last month’s Morton Games in Santry, feels she had a few more percent to give.

“I was hoping to go much faster. I had a great block of training before coming out here,” said Proper after the race.

“I was definitely hoping to PB and progress through the rounds. I’m quite disappointed but it was an okay run.

“If I came out of that saying everything went perfectly, then I would be worrying.

“I’ve had a very good season - that was my final race of the season - and I’m looking forward to building for next season.

“I felt great coming into it, I had a dream warm-up, but I just think I need to work a bit more on staying relaxed in the races.

“I have worked a lot of this but I have another couple of per cent to improve on and I think that will give me huge gains to my times for next year.

“I had great consistency this year, I really moved on in terms of my top-end speed. Things are going in the right direction.

“I’m a tiny bit away from everything coming together and running super-fast times.”

Earlier, Ben Reynolds in the 110m hurdles and Ciara Everard in the 800m bowed out in the first-round heats by finishing seventh in both of their races.

Holywood hurdler Reynolds came within 0.11 seconds of reaching the semi-finals of the hurdles, clocking a time of 13.72 seconds as Hansle Parchment of Jamaica took the honours in 13.33.

The North Down AC athlete would have got to the semi-finals had he been closer to his lifetime best of 13.48 set this season, but a recent niggle saw him sit out training the past eight days.

He was ninth fastest-loser when only the top four would make it, but Reynolds is enthusiastic about his Beijing campaign: “All in all I’m pleased with the race. Preparation had been awesome until most recently, and then not the most pristine recent eight days.

“I’ve been resting, so just pleased to be able to get going and produce a nice enough run.”

Everard was critical of her tactics after elimination in the heats of the women’s 800m.

The UCD athlete from Kilkenny finished seventh in her heat in a time of 2:03.98, just under three seconds slower than her lifetime best set at the Dutch IFAM meeting in Oordegem in May.

Poland’s Sofia Ennaoui won the heat in 2:01.16 after falling well off the back in the opening lap, with Everard well ahead in sixth.

However, the Irish athlete felt she should have moved up the field in the final lap instead of taking a place at the back of the bunch.

Having finished sixth at the Universiade World University Games in Gwangju last month, Everard said: “I think tactically I ran a really poor race, which is unlike me.

“I think I positioned myself well for the first lap, but then what kept happening was I had to break beyond girls to try and get a move going.”

– Will Downing, Beijing