The world championships in Beijing begin on Saturday, and there are five men to watch out for. Wayde van Niekerk: He holds the South African records for the 200m and 400m but it is in the longer distance that he has the best chance of bringing home a gold medal from Beijing.After a breakthrough 2014, the 23-year-old has the third-best time of this year in the 400m and has beaten Olympic champion Kirani James head-to-head over the single lap.Zharnel Hughes: A native of the Caribbean island of Anguilla, Hughes was cleared to compete for Britain in June and created some excitement by running a personal best of 20.05 seconds to win a wet 200m in London last month. The 20-year-old has been dubbed the "next Usain Bolt" and is a stablemate of the Jamaican great as well as 2011 world 100m champion Yohan Blake.Nijel Amos: Botswana's Amos has his best chance of winning a first major title in the 800m at Beijing. Amos has had injury problems after taking silver behind David Rudisha at the London Olympics but beat the Kenyan world record holder at last year's Commonwealth Games and again in Lausanne and London this season.Li Jinzhe: With high hurdler Liu Xiang now retired, China's long jump hope Li is one of the few men with a chance of offering the home crowd success. Trained by American Randy Huntington, who coached former world record holder Mike Powell, 25-year-old Li has struggled with technical problems this season after jumping a career best 8.47m outdoors and winning silver at the world indoors in 2014.Pedro Pablo Pichardo: With seven of the top 10 triple jumps of the year, including the top two, the 22-year-old former world junior champion looks set to vie with Olympic champion Christian Taylor, who owns the other three, for gold in Beijing. Cuban Pichardo managed his first two jumps over 18m - 18.06 in Doha and 18.08 in Havana - over two weeks in May, which took him to third. ..