After swimming the heat of the 4 × 200 freestyle relay at the 2001 World Aquatics Championships in Fukuoka, Japan, Hass was a spectator for the final, when the Australians set a world record of 7:04.66 mins. He went on to swim in the semifinal of the 200 m backstroke finishing 9th. At the 2002 FINA Short Course World Championships, Hass won a gold medal for Australia as part of the 4 × 200 m freestyle relay, swimming alongside compatriots Leon Dunne, Todd Pearson and Grant Hackett. Injury sidelined Hass in 2002, and despite representing Australia at the 2003 World Aquatics Championships in Barcelona, Spain, he never fully regained his earlier form.