1999 Sybase Open – Singles

Andre Agassi was the defending champion, but was defaulted in his second round match against Cecil Mamiit for swearing at a line judge.

Mark Philippoussis won the title, defeating Mamiit 6–3, 6–2 in the final.

Seeds
• # 🇺🇸 Pete Sampras (semifinals, withdrew because of an ankle injury)

• # 🇺🇸 Andre Agassi (second round, defaulted)

• # 🇦🇺 Mark Philippoussis (champion)

• # 🇺🇸 Michael Chang (semifinals)

• # 🇦🇷 Mariano Puerta (first round)

• # 🇺🇸 Jan-Michael Gambill (first round)

• # 🇦🇷 Mariano Zabaleta (first round)

• # Ramón Delgado (second round)