Pillay sliced 0.25 off the personal best he set in Boksburg last year, securing victory in 45.28 seconds.

Steven McElroy of the United States put up a fight against the rising South African star, but he was unable to stay in touch, earning the silver medal in 45.65. Yusuf Ali Abbas of Bahrain took bronze in the one-lap dash in 45.80.

While Pillay was the only SA athlete to step on the podium on Day 4 of the global junior showpiece, the national team narrowly missed out on a few medals, producing strong challenges in a variety of events.

After grabbing the bronze medal in the 100m sprint earlier in the week, Benjamin Richardson finished fourth in the men's 200m final in 20.55 in a fast race won by Israel's Blessing Afrifah in 19.96.

Anje Nel also took fourth place in the women's 400m hurdles final in a personal best 57.47, with American athlete Akala Garrett winning gold in 56.16. Another sprinter, youth athlete Precious Molepo, ended eighth in the women's 400m final in 53.49.

Earlier on the track, sprinter Viwe Jingqi won her 200m semi-final in 23.12, booking her place in the final to be held on Friday. Middle-distance runner Danielle Verster took fourth position in her 1 500m heat in 4:21.25, progressing to the final to be held on Saturday's last day of competition.

In the men's 4x100m relay, the SA team - Emel Keyser, Letlhogonolo Moleyane, Bradley Oliphant and Mukhethwa Tshifura - won their heat in 39.50, and they will turn out again in the final.

After four days of competition in Cali, the SA team had earned four medals (two golds and two bronze).

“Pillay has done us proud with the gold medal in a competition that has been tough for everyone. We are also very happy with the efforts of our athletes, most of whom are clocking personal bests and reaching the finals or semi-finals. We congratulate all medallists, their coaches, and support staff,” said Enoch Skhosana, the Acting President of Athletics South Africa.

Schedule of SA athletes, Day 5 (SA times):

Friday:

3.30pm - 10 000m walk, women (Janise Nell)

4.25pm - discus throw qualifying, men (Danie Strooh, Aron Alvarez Aranda)

5.40pm - 4x400m relay heats, women (SA team)

6.15pm - 4x400m relay heats, men (SA team)

10.00pm - long jump final, women (Karmen Fouche)

10.20pm - high jump final, men (Brian Raats)

11.30pm - 200m final, women (Viwe Jingqi)

Saturday:

1.00am - 4x100m relay final, men (SA team)