2003 Siebel Open – Singles

The 2003 Siebel Open was a men's international tennis tournament. Lleyton Hewitt was the defending champion but did not compete that year.

Andre Agassi won in the final 6–3, 6–1 against Davide Sanguinetti.

Seeds
A champion seed is indicated in bold text while text in italics indicates the round in which that seed was eliminated.


 * 1) 🇺🇸 Andre Agassi (champion)
 * 2) 🇹🇭 Paradorn Srichaphan (first round)
 * 3) 🇺🇸 James Blake (semifinals)
 * 4) 🇺🇸 Jan-Michael Gambill (second round)
 * 5) 🇺🇸 Todd Martin (second round)
 * 6) 🇮🇹 Davide Sanguinetti (final)
 * 7) 🇷🇺 Nikolay Davydenko (quarterfinals)
 * 8)  Kenneth Carlsen (quarterfinals)