The big, dominating and very popular 6-year-old mare, Zenyatta, and the 4-year-old colt, Blame, provided the most thrilling single sports event of this year.

These gallant animals performed the gripping spectacle in less than two minutes and three seconds eight days ago over a mile and a quarter in the Breeders’ Cup Classic at Churchill Downs where the usual annual excitement is the Kentucky Derby.

Despite staging one of her characteristic come-from-behind gallops that got her out with the leader for the stretch run, the previously undefeated Zenyatta lost by inches to Blame in the old gal’s 20th and final race of her glorious career. Blame’s margin of victory was officially listed as a head while it appeared to be much less and only about a nose.

The result is that Zenyatta goes off into the sunset of retirement to hopefully produce other spectacular racing thoroughbreds while Blame adds a great deal of luster to his resume as the only horse to ever beat Zenyatta, the grand dame of horse racing during the first decade of the 21st century.

All eyes were on Zenyatta from the start of the 12-horse race. The big mare went off as she had so many times — dead last. She fell to 15 lengths off the lead after half a mile. But Blame was also well behind at 10 lengths back in the middle of the field.

That's when Zenyatta did her usual thing and went into overdrive. The mare, who stands 17.5 hands and has huge strides when extending the gallop, began passing other horses easily as Blame did the same and worked his way through the crowd to get on top. Zenyatta went outside to make up lots of ground quickly.

These two made up enough ground to be one-two for the long stretch run at Churchill Downs. Then came the race for the wire that had most of the 72,739 fans screaming wildly for their favorite, Zenyatta. It is possible that many of the record 5.5 million persons watching the telecast were also screaming where ever they were.

But the big, dark bay gal failed by that narrow margin to repeat the Breeders’ Cup Classic victory she had a year ago at Santa Anita.

Those two Breeders’ Cup Classics were the only two races in her career when she went up against the boys. Her 18 other starts were victories in all-female races.

Many of her fans will probably continue to compare Zenyatta to other mighty thoroughbreds. There are some who have been claiming she was as good as Secretariat.

Such comparisons are really not valid unless the two horses in question raced against each other. Even time comparisons don’t mean much because of track conditions and other variables.

Yet there are two very famous thoroughbreds from years ago who, unlike Zenyatta, had rather short careers but, like Zenyatta, lost only once. One was Man O’ War, a colt, and the other was Ruffian, a filly.

The Blood-Horse magazine formed a panel of horse racing experts in 1999 in order to come up with a list of the leading 100 race horses of the 20th century. The results were put into a book, “Thoroughbred Champions: Top 100 Racehorses of the 20th Century”.

Man O’ War and Ruffian are fine examples of other one-time losers to remember because each was the leading horse of its sex in that top 100 list. In fact, Man O’ War was rated the No. 1 racehorse of the 20th century. Although Ruffian was the leading female in the top 100, she was only rated No. 35.

Secretariat was No. 2 and Citation No. 3 on that list. Secretariat, the 1973 Triple Crown winner, raced 21 times and lost five races. Citation, the 1948 Triple Crown champion, ran in 32 races and lost 13 times.

Man O’ War, bred and originally owned by August Belmont Jr., was foaled in 1917 and sold the next year to Samuel Riddle for $5,000, a goodly sum back then. Although “Big Red” as he was called lived to the ripe old horse age of 30 years, Man O’ War raced only 21 times.

He was put out to stud following his 3-year-old campaign in 1920 that ended with a victory in the Kenilworth Park Gold Cup at Windsor, Ontario, where he whipped, Sir Barton, the 1919 Triple Crown winner.

Big Red’s only defeat was suffered in his seventh race when he was a 2-year-old colt. It happened on August 13, 1919, in the Sanford Memorial Stakes at Saratoga 20 years before the present day starting gates were first used.

The old starting method was to line up horses behind a rope barrier or long pole that was lifted by the starter when the race began.

Man O’ War, a big, temperamental colt at 16.2 hands who was quite jumpy at times, was prancing about and made a couple of false starts in that Sanford Stakes. When the starter did raise the barrier to let the horses go, Man O’ War was turned completely around with his tail facing forward.

Jockey Johnny Loftus had to get Big Red straightened out and headed in the right direction, losing considerable ground in the realignment. But Man O’ War made up ground and ­nearly caught the leader, only to lose by less than half a length to a horse with the apt name of Upset.

Samuel Riddle kept Man O’ War out of the Kentucky Derby in 1920 to the displeasure of racing fans. Riddle felt 3-year-olds should not be required to run a mile and a quarter so early in May.

But then Big Red was entered in and won the Preakness and Belmont Stakes and probably would have won the Triple Crown if Riddle had thought differently about the KD distance in May.

Ruffian, unfortunately, had a tragic ending to her promising career. She, like Zenyatta, was a ­beautiful, big female standing 17 hands.

She was undefeated through 10 races when, as a 3-year-old, she went up against Foolish Pleasure, in a match race at Belmont Park, July 6, 1975. Foolish Pleasure had won the Kentucky Derby two months earlier while Ruffian won that year’s Filly Triple Crown that is now called the Triple Tiara.

The two horses started out at a very fast pace and Ruffian was ahead by a half length after three furlongs coming out of the first turn and heading into the backstretch. Suddenly Ruffian went down. She had suffered a severely shattered right foreleg when both sesamoid bones in that leg cracked.

Following hours of ­surgery, Ruffian came out of the anesthesia in her stall only to go berserk, throwing herself about and breaking her leg again. She had to be put down.

You just can’t compare Zenyatta with Man O’ War or Ruffian because one competed 90 years ago and one 35 years ago while the third competed up to a week ago. But just between you and me, I’d bet Zenyatta would finish _ in a three-horse race with those two.

Gordon White served 43 years as a sports reporter for The New York Times. His email is sports@thepilot.com.