The 2004 season proved to be a breakout year for Douma-Hussar. She had her best cross country finish at the 2004 World Championships, where her 17th place helped a Canadian team including Émilie Mondor, Malindi Elmore and Tina Connelly take the bronze medal in the short race. She won the 1500 m at the Boston Indoor Games and the Millrose Games and gained selection for the event at the 2004 IAAF World Indoor Championships. She made it to the final and ran a Canadian indoor record time of 4:08.18 minutes to take the silver medal behind Kutre Dulecha. She focused solely on the 1500 m track event and travelled to compete on the European outdoor track and field circuit. She won at the FBK Games in the Netherlands with a personal best of 4:04.85 minutes and was runner-up at the London Grand Prix. She was second at the national championships and was selected for the Canadian Olympic team for the first time. Her form peaked at the 2004 Athens Olympics as she made it to the final and ran a personal record time of 4:02.31 minutes to take ninth place. She ended the season with a fifth-place finish at the 2005 IAAF World Athletics Final.