Kirani James living up to his reputation achieved the first ever 200m and 400m sprint double when just as he had over one lap, he dominated the shorter sprint race.
James had the best start of the eight strong field and a powerful pick up saw him roar around the bend coming into the home straight a metre ahead of his rivals.
The lanky James then increased his stride, belting away down the home straight to stylishly collect a second gold medal and significantly reducing his personal best by 0.13 to 21.05.
Spain's Alberto Gavalda tracked James down the home straight best as he could and was rewarded with the silver medal and personal best of 21.33 with Keenan Brock beating fellow American Dedric Dukes for third place by 0.22 in 21.39.
James said: "Now I am a two-time world champion. I don't have a role model although Michael Johnson was a great runner.
The Grenadian whose displays have seen him compared to Usain Bolt, added: "I'm honoured but I want to take my own path and write my own history.
"I am proud to have won as a runner from the Caribbean because we don't have a lot of resources. We have significantly less resources than the US athletes.
Jodie at the double
Jodie Williams went into the history books when becoming the first ever girl ever to achieve the 100 metres and 200m sprint double.
Williams an easy winner of the 100m gold medal last Wednesday had always looked likely to add another to her tally with impressive displays in her 200 qualifiers.
The Herts/Phoenix 15-year-old confirmed that form in the final this afternoon although in a blitzing race she and Allison Peter of the US Virgin Islands were virtually inseparable.
Williams after a tense two minutes wait was given the decision and after a study of the photo-finish, both she and Peters were credited with a world leading time for the year of 23.08seconds.
Ashton Purvis in a repeat of the 100m placings, finished third and like the gold and silver medallists clocked a personal best of 23.15sec.
""This is my first international competition and now I am two-times world champion," said an elated Williams. "I only realised that I had won when I saw it on the display.
"Williams so close was the finish, admitted: "I thought I was second. This is the best feeling ever.
"I am speechless and shocked. Tonight I will celebrate."
The highly technical staff of Seiko confirmed that the fully automatic times of Williams and Peter were 23.074 and 23.076.
Kenya rules supreme
Cherono Koech with a fantastic burst of finishing pace in the final 200 regained the girls’ 800 title for Kenya last won by Flavious Kwamboka four years ago in Marrakesh.
Koech running a perfect race decimated her PB of 2:05.71 when storming to a a new championship record replacing the 2:03.40 Mariya Shapaeva of Russia set in 2003, and a world leading time for the year of 2:01.67.
Cuba's Rose Almanza after a little bumping and barging down the back straight, headed the field as it approached the bell (59.55) when Tizita Bogale of Ethiopia jumped the field.
The Ethiopian's break wasn't sustained and she was quickly hauled in before Koech with her determined assault rocketed around the final bend for an easy victory.
There was little between the chasing pack until coming down the home straight Ciara Mageean won Ireland's first medal of the championships and was followed home by Rowena Cole of Great Britain.
The pair who determinedly held off Almanza the world's number two this summer, were rewarded with huge personal bests of 2:03.07 and 2:03.83.
Koech despite arriving in the Sud Tyrol ranked seventh in the world, said: "I expected to win but I am still thrilled.
"I didn't even know that I could run this fast," she added, surprised after setting a championship record.
Koech leads Kenyan 1-2 in boys’ 3k
Isiah Koech may have won the 3000 gold medal but it was the fantastic performance of David Bett with a unforgettable break after 1200m which saw the title remain in Kenyan hands.
For the second successive championships the African nation occupied first and second positions and although he didn't win Bett made it so easy for himself and his team-mate.
Ethiopia's Fekru Feyisa took the field through the first kilometres in 2:45.96 and then 200m later Bett ranked second in the world rankings behind Koech, took off like a bullet.
He opened up a gap of around 20m but Koech gradually roped him in and at the bell the pair of uninhibited front runners were shoulder to shoulder.
The taller figure of Koech was content to sit on his companion's shoulder until unleashing his sprint finish to erase Ethiopia's Abreham Cherkos's six year old championship record and improving his world leader to 7:51.51.
Bett likewise substantially lowered his clocking 7:52.13 while Eritrea's Goitom Kifle a distant third also ran his fastest ever time of 8:05.83.
The winner acknowledging Bett's contribution, said: "We are focused on team work in Kenya and for it we have been rewarded with gold and silver."
Another Kenyan double in 1500
Gideon Mageka and Caleb Ndiku less than an hour later followed in the footsteps of their fellow 3000 gold and silver medallists Isiah Koech and David Beet with similar authoritive performances.
Their team running saw them dominate the race although with 800m remaining, arch Ethiopian rivals Girma Bekele and Zebene Alemayehu with Qatar's Mohammed Al-Garni, tried to disrupt them.
Alemamayehu and Al-Garni tried hanging on after a swift passage through the first two circuits, but after 1200m began wilting as the Kenyan duo increased the pressure and pace.
Bekele was dropped at the bell but managed entering the back straight to regain contact only to receive the biggest fright of his life.
Mageka and Ndiku with 250m remaining erupted, their massive injection of pace carrying them well clear to fight a domestic battle which continue until 50m from the line.
Mageka at that point drew ahead to win in a world leader and personal best - his previous stood at 3:40.00 - with Ndiku crossing the line in 3:38.42.
Bekele although blown away on the vital last finished third in a PB 3:39.88.
"This is my first proper international track meet which has motivated me more," said Mageka. "The race was really difficult because my team colleague pushed me.
"I come from a very simple home and now I want to have a (professional) career and my own manager."
Steeplechase also sees Kenya finish top
The gold and silver medal winning sequence of Kenya's distance runners continued in the 2000 steeplechase where despite his shocking hurdling style Hillary Yego won ahead of Peter Lagat.
Yego who controlled the first two kilometres with a first cautious split of 2:46.89 then a much quicker 2:38.44, eventually took the title in a world leading time where striking seven seconds from his previous best he clocked 5:25.33 with Lagat clocking 5:26.59.
His authority was only questioned twice, initially when Ethiopia's Desta Alermu tried to get on the Kenyan pair's shoulders with 300m remaining and was quickly blown away and left to finish third in a PB 5:29.66.
Then approaching the final water jump Lagat with a better technique, jumped him and came into the home straight looking good for the gold medal.
Yego refused to throw in the towel and in the last 30m accelerated past his fellow countryman for a fully deserved victory.
"This was a very hard race but I wasn't nervous at all," said Yego who trains with top Kenyan stars Edwin Soi and Patrick Terer.
First gold for Korea…
World leader Daniel Clemens who with a best of 5.35 stood head-and-shoulders above the rest of the pole vault field, looked the likely gold medallist after the qualifying round.
But the German never got his technique together and was on a precipice when having two failures with the bar at 5.15, he surprisingly passed his final jump.
Fellow countryman Carlo Paech in the same situation adopted exactly the same tactic with the same result, but with less failures took the silver on count back from Clemens.
That left the door open for Korean Minsub Jin who having equalled his PB with the bar at 5.10 went on after an initial failure to a lifetime best of 5.15.
…And for Chinese Tapei
Shih-Feng Huang only once approached his personal best of 74.75 but the furthest of his two 70m-plus throws of exactly 74 metres proved sufficient to win him the gold medal.
The Tapei's second round effort set the early standard with Frenchman Killian Durechou having his furthest effort of 73.54 in the next round which proved sufficient for second place.
Argentina's Braian Toledo on the day showed the most consistency with all of his five valid attempts over 70m. A personal best of 73.44 earned him the bronze medal.
The surprised winner, said: "I truly enjoyed this success - I just wanted to give it my best. I never thought I had a shot at winning."
Chinese favourite takes gold
Minjia Lu living up to her reputation as world number one (6.43) asserted her authority early in the long jump competition when flying out to a winning effort of 6.22 in the second round.
The Chinese girl claiming last summer's Olympic host nation's third gold medal of the championships, was never under any pressure in the last competition of a highly successful sixth World Youth Championships.
Romania's Alina Rotaru well below her best of 6.26 cleared 6.09 for the silver medal, while the USA's Jennifer Clayton with a best of 6.37 this year, managed just 6.05 for third position.
Medley Relays go to US
The United States dominated and finished by posting the fastest ever time of 1:50.33 replacing the 1:50.46 which earned Poland the gold medal in Debrecen eight years ago.
The 100 and 200 stages were closely contested but on the 300m leg Dedric Dukes powered away from the field to establish a healthy 20m lead for the defending champions.
Joshua Mance the 400m silver medallist gave it every ounce of energy left in his legs to shave the previous best.
Brazil in a tense finish where Jamaica's James Bell led into the home straight but fell and failed to finish, took silver in 1:52.66 narrowly ahead of Japan who clocked 1:52.88.
In the girls’ relay the United States may have dominated the race winning with a world lead of 2:04.32 but behind them there was a awesome battle for the medals between the other nations.
400m champion Ebony Eutsey took the baton for the eventual winner's with a lead of almost four seconds on the final 400 stint, but it would have taken the bravest of gamblers to put their money on who would win the other two medals.
Jamaica's Ristananna Tracey led coming into the home straight on the final leg but was quickly passed to finish sixth in a nail biting conclusion which went to the wire.
Hungary's Lilla Lorand grabbed the silver by just 0.03sec in a time of 2:09.22 from Romania's Adelina Pastor who held off Bahamian Katrina Seymour for the bronze by an equally tiny margin of 0.08sec.
David Martin for the IAAF