2001 AIG Japan Open Tennis Championships – Men's singles

Sjeng Schalken was the defending champion but lost in the quarterfinals to Michel Kratochvil.

Lleyton Hewitt won in the final 6–4, 6–2 against Kratochvil. With the victory, Hewitt became the last male player to win his debut event as a Grand Slam champion (having recently won the US Open) until Jannik Sinner in 2024.

Seeds
The top eight seeds received a bye to the second round.


 * 1) 🇦🇺 Lleyton Hewitt (champion)
 * 2)  Sjeng Schalken (quarterfinals)
 * 3) 🇩🇪 Rainer Schüttler (third round)
 * 4) 🇸🇪 Jonas Björkman (third round)
 * 5)  Michel Kratochvil (final)
 * 6) 🇺🇸 Michael Chang (third round)
 * 7)  Marcelo Ríos (quarterfinals)
 * 8) 🇪🇸 Francisco Clavet (quarterfinals)
 * 9) 🇩🇪 Lars Burgsmüller (third round)
 * 10) 🇮🇱 Harel Levy (second round)
 * 11)  Nicolás Massú (third round)
 * 12) 🇦🇺 Andrew Ilie (first round)
 * 13) 🇪🇸 Álex Calatrava (first round)
 * 14) 🇦🇺 Wayne Arthurs (second round)
 * 15) 🇺🇸 Michael Russell (third round)
 * 16)  Ramón Delgado (second round)