In the following month he contested a similar event at Fair Grounds Race Course in New Orleans and recorded his first success finishing strongly to win by a length and a quarter having been outpaced in the early running.
On January 19 he was stepped up in class and distance for the second running of the one mile Smarty Jones Stakes and won by three and a half length after taking the lead on the final turn.
In the Grade II Arkansas Derby in April he raced behind the leaders for most of the way but made no impression in the straight, finishing sixth behind Papa Clem, with the future Belmont Stakes winner Summer Bird in third.
In the following month he was moved up to Grade I class for the first time when he contested the Stephen Foster Handicap at Churchill Downs and finished sixth of the eleven runners behind Pool Play.
Alex Solis took over the ride on Flat Out when the horse started the outsider in a field of six for the Grade II Suburban Handicap over nine furlongs at Belmont Park on July 2.
For the rest of the season, Flat Out was campaigned exclusively in Grade I class, beginning with the Whitney Handicap at Saratoga in August in which he finished second to the six-year-old Tizway.
"[11] On November 5 Flat Out started favorite for the Breeders' Cup Classic at Churchill Downs against a field which included Havre de Grace, So You Think, Uncle Mo, Game On Dude, Ruler on Ice and Drosselmeyer.
On August 4 at Saratoga he again ran in the Whitney and finished third to Fort Larned and Ron the Greek after being forced to race on the wide outside on the final turn.
Making relentless progress he caught the long-time leader Stay Thirsty in the last stride to win by a head, with a gap of five and a half lengths back to Fort Larned in third.
Flat Out's final race of the season was the Breeders' Cup Classic at Santa Anita Park on November 3, when he started third favorite in a field which included Game On Dude, Mucho Macho Man, and Fort Larned.
Ridden by Junior Alvarado he produced his customary strong late run to catch Cross Traffic in the final strides and win by a head in a time of 1:32.99.
He settled in second place behind Percussion before taking the lead on the final turn and drew away to win comfortably by two and a half lengths and a nose from Last Gunfighter and Fast Falcon.
He was made the 2.5/1 favorite at the head of a field which included Alpha, Ron the Greek and Cross Traffic as well as the leading three-year-old colts Orb and Palace Malice, winners of the Kentucky Derby and Belmont Stakes respectively.
Flat Out's third attempt at the Breeders' Cup Classic proved to be his least successful as he was never in serious contention and finished eighth of the eleven runners behind Mucho Macho Man.
Flat Out overtook the leader Private Zone inside the final furlong and won by one and a half lengths with Verrazano third and Groupie Doll in fourth place.