Brazilian officials said they hoped sprint king Cesar Cielo would shrug off the distractions of a high-profile doping case after he was cleared to compete at the Shanghai world championships. Olympic champion Cielo trained in the Sea Crown indoor stadium on Friday, a day after arbitration officials dismissed calls by world swimming body FINA for a suspension after he tested positive for a banned diuretic. A spokesman for the Brazilian team told AFP that the team would support their biggest star but it was difficult to judge the impact of the case on Cielo's preparations for defending his 50m and 100m freestyle titles. When asked whether Cielo was confident about retaining the gold medals he won at the 2009 Rome worlds, the spokeswoman said late Thursday: "We don't know. After all this we don't know but we are there to support him." She added that the 24-year-old had continued to train during his ordeal. Cielo, Nicholas dos Santos and Henrique Barbosa were all let off with warnings after they tested positive for furosemide. But team-mate Vinicius Waked was banned for a year for a second drugs violation. The Court of Arbitration for Sport (CAS) announced the decision on Thursday, one day after a six-hour hearing in Shanghai, attended by the four. The four swimmers tested positive for furosemide, which can be used to mask performance-enhancing drugs and is banned by the World Anti-Doping Authority, at Brazil's national championships. CAS said the four blamed a contaminated caffeine supplement for the test results, adding that it would issue a detailed statement in the next few weeks. Cielo took 50m freestyle gold at the 2008 Beijing Olympics in an Olympic record time of 21.30 seconds. The following year he bagged the 50m and 100m titles at the Rome worlds, breaking the championships record in the 50m and setting a new world mark of 46.91 in the 100m. He continued his astonishing run of success in December that year, smashing the 50m world mark on home ground in Sao Paulo, touching in 20.91sec. And last year he underlined his dominance in the sprint events, winning the 50m freestyle and 100m freestyle at the short course world championships. Cielo and the other swimmers had been let off with a warning by the Brazilian federation. But unhappy with that decision, FINA took the case to CAS, calling for bans and for the swimmers to be stripped of all their results since they failed the tests in May. Governing body FINA has tightened its anti-doping procedures at the Shanghai championships by reintroducing blood testing, alongside urine sampling, for the first time since 2005. FINA executive director Cornel Marculescu also issued a reminder that athletes had to take responsibility for the contents of their vitamins and food supplements. The blue riband swimming events at the Shanghai worlds kick off on Sunday. The 100m and 50m competitions start on Wednesday and Friday.