Agassi, runner-up to Pete Sampras in 2002, will be hoping to live up to his top billing when the year's final grand slam gets underway in New York next Monday.
The last time the American entered the tournament as the number one seed, in 2000, he lost in the second round.
Having won the event twice, Agassi is one of only three former champions in the men's draw.
Sampras, winner of the hardcourt slam five times since 1990, has not played competitively since capturing his 14th grand slam crown at the Open 12 months ago.
Although he has yet to announce his retirement, the 32-year-old will not defend his title.
Australia's Lleyton Hewitt, seeded sixth, and Russia's Marat Safin in 26th are the other former champions in the field.
Switzerland's Roger Federer, who emerged victorious at Wimbledon last month, has been seeded second while French Open winner Juan Carlos Ferrero is third.
ARGENTINE CHALLENGE
Among the new generation of Americans, Andy Roddick, twice a grand slam semi-finalist this year, and Mardy Fish have been slotted in fourth and 24th respectively.
Fifth seed Guillermo Coria will lead a strong Argentine challenge at Flushing Meadows.
He is joined by compatriots David Nalbandian in 13th spot, Agustin Calleri (19th), Mariano Zabaleta (27th) and Gaston Gaudio (30th).
Newly-crowned world number one Clijsters heads the women's draw while her fellow Belgian Justine Henin-Hardenne is second.
With Serena Williams unable to defend her title after undergoing knee surgery earlier this month, this marks the first time that Belgium players occupy the top two spots at a grand slam.
It is also the first time in 32 years that both the men's and women's champion will not defend their title. In 1971, holders Ken Rosewell and Margaret Court skipped the event.
Henin-Hardenne, who claimed the French Open in June, has been elevated one place above her world ranking following Williams's withdrawal.
Clijsters -- the only player to be ranked number one without winning a grand slam title since WTA rankings were introduced in 1975 -- will be bidding to achieve her breakthrough at the Open.
Americans Lindsay Davenport and twice champion Venus Williams -- who has not played since losing the Wimbledon final to her sister Serena last month -- have been seeded third and fourth.
The draw for the U.S. Open, which will be held from August 25 to September 7, will be made on Wednesday.
