Angelica Bengtsson - 4.58m in Sollentuna (DECA Text&Bild) © Copyright
Adam Gemili GBR - 100m
The 18-year-old sprinter has put behind him a promising football career and leads this year's rankings with the 10.08m he clocked in the German town of Regensburg last month. He has also been selected for the Great Britain team that will compete on home soil at the 2012 Olympic Games in London.
Tyreek Hill USA - 200m
Hill ran 20.14 back in May, just one-hundredth away from Roy Martin's 27-year-old US junior record, and the man from Georgia was in good form at the US Junior Championships as well. Possibly only Jamaica's Julian Forte can stay with him.
Luguelín Santos DOM - 400m
Dominican Republic's 2010 Youth Olympic Games winner has had a series of sparkling performances on the international circuit against senior opposition, including clocking 44.45 to win at the IAAF World Challenge meeting in Hengelo to become the third fastest junior ever.
Sergey Morgunov RUS - Long Jump
The Rostov teenager, who also won at the European Athletics Junior Championships last year, flew out to a world junior record of 8.35m at the Russian junior championships in Cheboksary, breaking a mark that had stood for nearly 40 years. He is the only junior in the world over eight metres this year.
Jacko Gill NZL - Shot Put
Gill will be defending his World Junior Championships title that he won two years ago in Moncton, Canada, before he went on to win at the World Youth Championships last year. He is over a metre ahead of his nearest rival on the 2012 rankings.
Faith Chepngetich Kipyegon KEN - 1500m
She will be looking to add another world title to the ones she won at the World Youth Championships and World Cross Country Championships in 2011. Kipyegon has run 4:03.82 this year, nearly five seconds faster than the next best junior in the world. She has also been selected for Kenya's Olympic Games squad.
Buze Deriba ETH - 5000m
She has raced sparingly this year but her personal best of 15:11.53, achieved in France last month, makes her 13 seconds faster than anyone else on the start line in Barcelona.
Angelica Bengtsson SWE - Pole Vault
Another of a small group of athletes defending their titles from two years ago, Bengtsson confirmed that she's in great shape by going over a world junior outdoor best of 4.58m on home soil in Solletuna last Thursday, a mark only succeeded by her world record of 4.63m achieved indoors last year.
Liuba Zaldívar CUB - Triple Jump
Has not jumped anywhere outside Cuba until the CAC Games in El Salvador - and solely in Havana since 2010 - so the World Junior Championships will be her second overseas trip but she has consistently been well over 13 metres and has a best of 13.91m. She will be looking to follow in the footsteps of her compatriot Dailenys Alcántara, who won in 2008 and 2010.
Anna Rüh GER - Discus
Rüh threw 63.14m, the best distance by a junior anywhere in the world since 1998, at the German national championships last month and the Neubrandenburg thrower has had a series of other impressive performances this summer, including finishing fourth at the recent European Athletics Championships.
Phil Minshull for the IAAF