By Nick MulvenneyWayde van Niekerk lit up the Bird’s Nest with a stunning 400 metres run to win a first sprint gold for South Africa and cap a night of exceptional performances at the World Athletics Championships on Wednesday.Two of those came in the men’s javelin and women’s 3,000 metres steeplechase where Kenyans Julius Yego and Hyvin Jepkemoi added another two gold medals to the East African powerhouse’s already considerable haul.The scourge of doping returned to haunt the sport, however, when two of their compatriots were provisionally banned for failing drug tests on the eve of the championships.Part two of the sprint showdown between Usain Bolt and Justin Gatlin, which for many has encapsulated the doping crisis that has tarnished the sport over the last month, also moved a step closer.The fact that Bolt has never failed a dope test while Gatlin has served two drug bans provided the backdrop for their first meeting in Sunday’s 100 metres final, from which the Jamaican emerged triumphant.Gatlin’s run of 19.87 seconds to win his 200m semi-final on Wednesday was the second fastest ever at that stage of a world championships, however, and will give him confidence he can end Bolt’s six-year grip on the title in Thursday’s final.“I think that I have a lot left in the tank,” the 33-year-old American said. “I just have to control the race … and I think we’ll be able to bring it home.”Bolt also looked in fine form, though, and took time to chat to a fellow competitor as he approached the line to win his heat with his first sub-20 second time of the year (19.95).“I can’t complain,” he said. “I’m happy with my form. I just did what I had to do.”For once, though, the 29-year-old was not the most impressive performer on the track with that honour going to Van Niekerk.Racing against a field containing a record five sprinters who had run under 44 seconds, the 23-year-old dominated the contest from start to finish and crossed the line in 43.48 seconds.The effort of running a time that only American world record holder Michael Johnson and his compatriots Butch Reynolds and Jeremy Wariner have bettered took its toll, however.Van Niekerk collapsed on the track at the end of the race and was taken to hospital with his “vital signs unstable”, the IAAF’s medical delegate said, leaving runner-up LaShawn Merritt to hail the quality of the race.“It’s crazy. We’re warriors. We’re animals,” said the American 2013 world champion, whose personal best 43.65 was good enough only for silver ahead of Olympic champion Kirani James (43.78).Van Niekerk was discharged just before midnight local time.While Van Niekerk’s time was the best since 2007, you would have to go back as far as 2001 to witness a javelin flying as far as the 92.72 metres Yego managed to give Kenya its first world title in a field event.To the diminutive Yego, who learned the javelin from watching videos on the internet after being rejected as a runner, fell the duty of reacting to the positive dope tests of his team-mates Koki Manunga and Joyce Zakary.“It’s a shame,” he said. “I always believe we can win clean so it’s a shame to them.”Jepkemoi produced a performance more typical of her nation to win the steeplechase, outsprinting favourite Habiba Ghribi of Tunisia and German Gesa Krause down the home straight to win Kenya’s sixth gold in nine minutes, 19.11 seconds.Zuzana Hejnova already knew her race was won when she went over the final obstacle in the 400 metres hurdles and the Czech, who ran the year’s best time of 53.50 seconds, became the first woman to successfully defend the world title in the event.A thrilling women’s pole vault contest featuring Cuba’s Yarisley Silva, Brazil’s Fabiana Murer and Greece’s Nikoleta Kyriakopoulou kept the crowd engrossed all evening in the gaps between the other events.Silva took the title when she cleared 4.90 metres at the third attempt, leaving Murer, one of her country’s best hopes of gold in athletics at next year’s Rio de Janeiro Olympics, with silver and Kyriakopoulou claiming the bronze.