Both the men's and the women's events took place at the Ariake Coliseum in Tokyo, Japan, from September 29 through October 5, 2008.

5, Valencia and 's-Hertogenbosch winner, Tokyo defending champion David Ferrer, Dubai, San Jose and Beijing champion Andy Roddick, and Olympic silver medalist, Viña del Mar, Munich titlist Fernando González.

Also present were Stuttgart finalist Richard Gasquet, Stuttgart, Kitzbühel, Los Angeles, Washington winner Juan Martín del Potro, Tommy Robredo, Jo-Wilfried Tsonga and Mikhail Youzhny.

The women's line up included Stockholm and New Haven champion Caroline Wozniacki, Fes and Portorož runner-up, Strasbourg winner Anabel Medina Garrigues, and Wimbledon semifinalist Jie Zheng.

Other seeded players were Estoril, Barcelona and Seoul titlist Maria Kirilenko, French Open quarterfinalist Kaia Kanepi, Shahar Pe'er, Tamarine Tanasugarn and Aleksandra Wozniak.