Swimmer Matthew Cowdrey became Australia\'s most decorated Paralympian on Wednesday, smashing his own world record as he claimed an historic 11th gold medal. The 24-year-old, an amputee since childhood, finished the S9 50m freestyle in a new world best of 25.13sec -- leaving Tamas Toth of Hungary to pick up the silver and Spain\'s Jose Antonio Mari Alcaraz to take the bronze. Cowdrey has already won two golds in the S9 100m backstroke and the 4x100m freestyle relay 34 points, as well as two silvers in the S9 100m butterfly and SB8 100m breaststroke. He is still to race in the S9 100m freestyle and SM9 200m individual medley. He won five gold and three silver medals in Beijing four years ago, and broke five world records. In Athens in 2004, he won three golds. Meanwhile, US swimmer Jessica Long of the United States and Oxana Savchenko both set fresh world records as they claimed a fourth gold medal each. Long won the SM8 200m medley and Savchenko the SM12 100m backstroke. Ian Jaryd Silverman of the United States, 17, also set a new world best in the S10 400m freestyle, thwarting Brazil swimming star Andre Brasil\'s bid for a third gold. \"I am definitely disappointed,\" said Brasil, 28. \"There are some different guys appearing on the scene now, like Ian. They\'re so young.\" Britain\'s Oliver Hynd won gold in the SM8 200m medley, adding to the silver and bronze he has already collected in his first Paralympics. \"I don\'t believe it -- it\'s amazing,\" said the 17-year-old, whose older brother Sam came fourth in the race. \"I thought, \'It can\'t be right\'. But I\'m Paralympic champion and I\'m over the moon,\" he told Britain\'s Channel 4 News.