Haustov made his first Estonian team at the 2004 Summer Olympics in Athens. He qualified for two swimming events by attaining B-standard entry times of 23.08 (50 m freestyle) and 50.42 (100 m freestyle). In the 100 m freestyle, Haustov raced to sixth place on the fifth heat and thirty-fifth overall by 0.35 of a second behind Finland's Matti Rajakylä in a time of 51.02. In his second event, 50 m freestyle, Haustov set his personal best of 23.52 seconds, but rounded out the sixth heat to last place and forty-ninth overall by 0.02 of a second behind Chinese Taipei's Wang Shao-an.