In 2004, the Austrian reached his first third round of a Grand Slam at the 2004 Australian Open with victories over Tomas Behrend, and Galo Blanco, before losing to Sjeng Schalken. Melzer made his Master Series debut at the 2004 Indian Wells Masters, losing to Victor Hănescu. He then won his first Master Series matches at the 2004 Miami Masters with victories over Ivo Karlović, and then world no. 8 Tim Henman, but lost to Todd Martin in straight sets in the third round. He next reached the quarterfinals of the 2004 Hamburg Masters with victories over Nicolás Massú, Irakli Labadze, and Marat Safin, but lost to former world no. 1 Lleyton Hewitt. Melzer then reached the semifinals of the 2004 Internationaler Raiffeisen Grand Prix, losing to Xavier Malisse in three sets. He then won his first French Open match over Wayne Ferreira, but then lost to Lleyton Hewitt in four sets.