Fifty years ago today, Secretariat broke the record for the fastest Kentucky Derby. When 20 horses break from the gates on Saturday in the 149th Run for the Roses, they’ll still be chasing Secretariat’s record of 1 minute, 59.4 seconds over the 1.25-mile course at Churchill Downs.

Last year, 80-1 long shot Rich Strike won the Kentucky Derby on a fast track and came home more than three seconds slower than Secretariat had.

While Secretariat had 11 races before the 1973 Kentucky Derby, the colt took the first steps at Churchill Downs toward the kind of fame and celebrity that few, if any, horses have achieved when he won the 99th Run for the Roses.

Winning the Kentucky Derby put Secretariat on the road to the Triple Crown. After seven Triple Crown winners in a 19-year span, thoroughbred racing hadn’t had a horse win the Kentucky Derby, Preakness Stakes and Belmont Stakes since Citation in 1948.

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At the Kentucky Derby, Secretariat went off as the betting favorite at 3-2, but not a heavy favorite over Santa Anita Derby winner Sham, who was at 2-1.

Secretariat had been the 2-Year-Old Horse of the Year, but he came into the Kentucky Derby off a third-place finish, the second-worst of what turned out to be a 21-race career (behind a fourth-place finish in his first outing).

At the Wood Memorial on April 21, 1973, Secretariat had finished behind his stablemate Angle Light and Sham at Aqueduct.

Before the Wood, Secretariat hadn’t been beaten to the finish line in his previous 10 races, although at the Champagne Stakes at Belmont Park on Oct. 14, 1972, he had been relegated to second place when track stewards ruled Secretariat had interfered with second-place finisher Stop the Music in the stretch run.

Trainer Lucien Laurin blamed Secretariat’s showing in the Wood on an abscess in the colt’s mouth, which burst the Sunday before the Kentucky Derby.

But some handicappers had another theory: While Secretariat’s sire Bold Ruler had passed his speed of his son, he had faded to a fourth-place finish as the favorite in the 1957 Kentucky Derby. If Secretariat couldn’t cut it in the 9-furlong Wood Memorial, could he be expected to fare any better in the Kentucky Derby, which was a furlong longer?

Secretariat provided the answer as jockey Ron Turcotte brought “Big Red” from the back to sweep around the field until running past Sham in the stretch for a 2.5-length victory.

Secretariat broke the Kentucky Derby record of two minutes flat established by Northern Dancer in 1964 by covering the final one-quarter mile in 23 seconds. During the race, Secretariat ran each successive one-quarter-mile stretch faster than he had the previous one.

The victory was worth $155,050 and made the Laurin-Turcotte combination a back-to-back winner in the Kentucky Derby. The trainer-jockey team had won in 1972 with Riva Ridge.

Secretariat would enter the Preakness Stakes two weeks later as the Triple Crown hopeful for 1973 and seeking to become the eighth horse since Citation to win the first two legs of the Triple Crown.

Mark Inabinett is a sports reporter for Alabama Media Group. Follow him on Twitter at @AMarkG1.