The Marlboro Cup Invitational Handicap was a Thoroughbred horse race first run in September 1973 at Belmont Park in Elmont, New York.
Such was the drawing power of Secretariat that CBS television readily agreed to broadcast the race nationally, a rare occurrence at the time for a non-Triple Crown or traditional "classic" event (such as the Travers Stakes).
Originally conceived as a match race with Secretariat's stablemate and 1972 Kentucky Derby winner Riva Ridge, it was changed to an invitational race that brought together the top horses 3 years of age and older.
In the inaugural race, Secretariat set a world record time for 1+1⁄8 miles on dirt while winning by 3+1⁄2 lengths on a track officially rated as being only "good".
(The two met again in that year's edition of the Jockey Club Gold Cup; Seattle Slew lost by a nose to Exceller, while Affirmed finished up the track due to a slipped saddle.