Tina Clayton successfully defended her women's 100m title at the World Athletics Under-20 Championships after she ran a championship record 10.95 seconds (-0.1m/s), also lowering her own national junior record at the Pascual Guerrero Olympic Stadium in Cali, Colombia, Wednesday night.
It was gold and silver for Jamaica as Serena Cole took the silver in 11.14 seconds, just off her personal best 11.13 seconds with American Shawnti Jackson third with a personal best 11.16 seconds.
Clayton's time matched that of her compatriot Elaine Thompson-Herah to win the women's 100m title at the Commonwealth Games in Birmingham as the teenager repeated her win from Nairobi, Kenya last year.
Most of the afternoon session was delayed by two hours after a fierce thunderstorm halted proceedings, but Clayton rose to the occasion with a masterful performance, opening the throttles for the first time and running away from the field.
She had looked subdued in the first two rounds, including the semi-finals run earlier in the afternoon, but once the gun went in the final, there was no catching her as she streaked away from a strong field.
The two medals saw Jamaica move up from ninth to third place on the table with five — a gold, three silver and a bronze.
Another eight athletes will make their first appearance on today's fourth day of competition, including men's triple jump world leader Jaydon Hibbert who will be taking part in the preliminaries, along with Royan Walters.
Hibbert, the national senior champion in the 'hop skip and jump', is unbeaten in the event all year and has a personal best 16.66m, half a metre better than anyone else, so far.
Kerrica Hill, who ran a World Youth Best 12.98 seconds in the 100m hurdles and CARIFTA Games champion Alexis James, will fly the Jamaican flag in the event, while Brianna Lyston and Alana Reid will contest the first rounds of the women's 200m.
J'Voughnn Blake and Adrian Nethersole will line up in the men's 800m, while the first rounds of the men's and women's 4x100m relays will also be contested.
In the semis of the women's 100m, Clayton looked easy, winning in 11.17 seconds (-0.1m/s) while shutting down after about 50 metres.
Cole was second in her semi-final, running 11.29 seconds (0.5m/s) beating by the impressive Tima Seikeseye Godbless of Nigeria who won with 11.20 seconds.
Demario Prince failed to finish the 110m hurdles, hitting the last two hurdles and got tangled in the 10th and ended up on the track.
Antoine Andrews of the Bahamas won in a joint world leading 13.23 seconds (0.2m/s), beating American Malik Mixon who ran a personal best 13.27 seconds with favourite Matthew Sophia of the Netherlands third in a national junior record 13.34 seconds.
Meanwhile, Bryan Levell, Jamaica's only athlete in the event, qualified for the final of the men's 200m after winning his semi-final heat in a personal best 20.34 seconds (0.1m/s), beating his previous best of 20.53 seconds set in March this year.
Earlier in the day he was third in his first round heat in 20.85 seconds.
Sandrey Davison, who was set to run the event, was injured in the semi-finals of the men's 100m on Tuesday.
Litsile Tebogo of Botswana, the men's 100m champion looks set for the double after he romped to a championship record 19.99 seconds in the first round, then cruised to a more pedestrian, by his standards, 20.23 seconds in the semis.
Dejeanae Oakley qualified for the finals of the women's 400m after she was second in her semi-final heat yesterday in 52.29 seconds, beaten by India's Rupal who ran a personal best 52.27 seconds.
Rickianna Russell missed advancing after she was sixth in her semis in 54.44 seconds.
Both Delano Kennedy and Shaemar Uter ran personal bests to qualify for today's men's 400m final which promises to be one of the events of the day if not the championships.
Kennedy won his semi-final in 45.49 seconds, his second life time best of thr week after he ran 46.24 in the first round and came into the championships running 46.58 seconds.
Uter also lowered his personal best to 45.96 seconds to place second in his semis race, beating his previous best of 46.09 seconds.
Two Jamaicans advanced in the men's 400m hurdles as Roshawn Clarke ran 50.71 seconds, third best overall, while Antonio Forbes was comfortable with 52.45 seconds in his heat, both advancing as winners.
Oneika McAnuff was sixth in her semi-finals of the women's 400m hurdles, in 59.74 seconds and failed to make it to the final.