On 25 March 2007 he won the silver in the 400 m freestyle (3:45.12) at the 2007 World Championships in Melbourne, Australia. Three days later, on 28 March, he swam to the first Tunisian World Championship in swimming in winning the 800m freestyle in a then African Record of 7:46.95 — one of the top 10 fastest times ever. However, due to his positive drug-testing result from a in-competition test from December 2006 and the 18-month competition ban imposed on him on 11 September 2007 by the Court of Arbitration for Sport (CAS), retroactive from 30 November 2006 forward, his 2007 World Championships results have been nullified. He was also a finalist in the 400 m individual medley, where he originally finished fourth in 4:11.68.