Defending US Open champion Pete Sampras officially withdrew from this year's tournament Wednesday. Andre Agassi, who he beat in last year's final, will be the top seed.
Sampras was automatically included on the initial entry list last week based on his No. 26 ranking. He has not played a professional tournament since winning his fifth US Open, and record 14th Grand Slam singles title, last year.
He is the first US Open men's singles champion not to defend his title since 1970 winner Ken Rosewall. Sampras told NBC-TV last weekend that "there's a good chance" he will officially retire soon.
Agassi, a two-time US Open champion, is currently the world's top-ranked player. The 33-year-old Agassi, this year's Australian Open champion, is the oldest player to be ranked No. 1 by the ATP.
Agassi has won eight Grand Slam titles, tying him for sixth on the career list.