Williams-Darling had a breakout year in 2004. She started with a bronze medal at the 2004 IAAF World Indoor Championships in Budapest, Hungary, running a personal best behind Russia's Natalya Nazarova and Olesya Krasnomovets. Then in July, at the Rome meeting of the IAAF Golden League, Tonique broke Mexican world champion Ana Guevara's 23 race winning streak in the 400 meter race.