Kenya's Faith Kipyegon won a tight and dramatic women's 1500m final on Monday evening, upgrading her world silver from Beijing 2015 to gold in 4:02.59, ahead of US champion Jenny Simpson (4:02.76) and South Africa's Olympic 800m champion Caster Semenya (4:02.90).
"I thank God today, it was a good race in London,” Kipyegon said. “It is such a high quality field. The best was going to win here.”
"It was always going to be quick and competitive. I'm looking forward to celebrating this with my family."
Caster Semenya's bronze was Team South African third medal of the IAAF World Championships in London.
"I knew I was going to win a medal, so it (the middle-distance double) was not a big deal for me," said Semenya, who is due to compete again in the 800m heats on Thursday.
"I'm really happy with the bronze. Obviously a lot can not go your way in a final, so to come out with a bronze is amazing but I was hoping for a better time.
"1500m is a tactical race, I tried to find my own space but fortunately I managed to get away with the bronze so I am happy."
"I believe in myself and now we have a medal in the pocket."
Elsewhere for team South Africa...
Earlier on Day 4 of the global spectacle, world 400m record holder Wayde van Niekerk won his 200m heat in 20.16 seconds and Akani Simbine was second in his race in 20.26, with both athletes progressing to the semifinals on Wednesday.
Though SA junior record holder Clarence Munyai ended third in his heat in 20.19, producing a fine performance of his own, he was unfortunately disqualified for stepping out his lane on the bend.
The SA team filed an appeal but the decision was upheld.
Wenda Nel did well to take second position in her 400m Hurdles heat in 55.47, booking her place in the semifinals of her event, set to be held on Tuesday.
“Congratulations to all our athletes for bringing in the three medals for South Africa!” said Aleck Skhosana, the President of ASA.
“To the athletes who are progressing to the next rounds, we urge them and their supporting teams to do anything and everything to keep athletes focused on the job.
“We thank all the coaches for the sterling job so far and expert more as usual. We still have so many days to go, so discipline and focus to the core business, is critical.
“Flying the flag of SA is our theme, but reaching the finals and winning a medal, is our objective. We have for now achieved the same number of medals as in Beijing 2015 World Championships.
“We are hoping that it is still possible to get some medals in the remaining events to set a better mark.”