SHANGHAI (AFP) - Brazilian swim star Cesar Cielo escaped a drugs ban Thursday after a high-profile case that left him clear to defend his 50m and 100m titles and lifted a doping cloud from the world championships. The Olympic champion was let off with a warning after testing positive for a banned diuretic, despite calls for a three-month suspension which would have sent him home from Shanghai and interrupted his build-up to London 2012. The Court of Arbitration for Sport (CAS) dismissed appeals by world body FINA to ban Cielo and team-mates Nicholas dos Santos and Henrique Barbosa, who also failed a test for furosemide in May. But CAS, which held a six-hour special tribunal in Shanghai Wednesday, slapped a one-year ban on another Brazilian, Vinicius Waked, because it was his second drugs violation. "The CAS panel... decided to dismiss the appeals filed by FINA against Cesar Cielo, Henrique Barbosa and Nicolas dos Santos and to confirm the (Brazilian federation's) decision concerning them," the body said. Cielo, who is also the world record-holder in both freestyle sprints, had denied wrongdoing and appeared relaxed and upbeat at the CAS tribunal, where he was represented by specialist sports doping lawyer Howard Jacobs. "What I can tell you is that the bottom line is that they did not act with fault or negligence in the case," said Brazil-based lawyer Marcelo Franklin, who was also part of the legal team. "They always believed they would have a good award so it never passed through their mind they would have any period of suspension so of course they are relieved right now," he told AFP. The case had threatened to become one of swimming's most high-profile scandals since the dark days of the 1980s, when East German swimmers dominated, only to be caught cheating by using drugs. The swimmers blamed a contaminated caffeine supplement for their failed tests for furosemide, which can be used to mask performance-enhancing drugs. "The Brazilian swimming federation and all the athletes and the coaches are very happy with this result," a spokeswoman for the Brazilian team told AFP. "They are very happy with the fact that the Brazilian position was maintained." Attention will now swing decisively back to the action at the Oriental Sports Centre, where hosts China took a giant stride towards a historic sweep of all 10 diving medals. Chen Ruolin and Hu Yatan led a one-two in the women's 10m platform event, relegating Mexico's defending champion Paola Espinosa to the bronze position and handing China seven titles out of seven so far. And six days after competition started, the USA finally bagged their first medal of the championships with victory in the 5km team swim, an event not raced at the worlds since 1998. Andrew Gemmell, Sean Ryan and Ashley Twichell completed the Jinshan City Beach course in 57min 0.6sec, more than a second ahead of the Australian team with Germany taking bronze. The win places the United States equal fourth on the medals table alongside Britain and behind hosts China, Russia and Greece. Most of the 15 golds handed out so far have been for diving and synchronised swimming. But America will be expected to dominate the second week of competition when their swim stars led by 14-time Olympic champion Michael Phelps take to the newly built Sea Crown indoor pool. Phelps, returning to China after his record-breaking eight-title haul at the Beijing Olympics, touched down in Shanghai on Wednesday after a training camp in eastern Australia. The 26-year-old superstar could swim up to seven events as he looks to kick-start his London 2012 build-up after a bumpy season in which he has lost three times in the 200m butterfly, ending a nine-year winning streak. Meanwhile Russia claimed gold in the synchronised swimming free combination, extending their dominance of the event. China were second and Canada placed third.