Ever since Affirmed won the Triple Crown in 1978, racing fans have wondered when the next 3-year-old would repeat the feat. The latest colt prompting such speculation was Uncle Mo, who has since gone to the sidelines.

But when Animal Kingdom rolled to an emphatic victory in Saturday's Kentucky Derby, he reignited the Triple Crown talk. Better still, the Team Valor International homebred has the profile to get the job done.

The Triple Crown has been exceptionally difficult to win, with only 11 horses having done so, the first time Sir Barton in 1919. Some of the sport's most outstanding champions have come up short, confounded by a plethora of pitfalls — bad luck, injuries, lack of stamina, or just the physical grind itself of three races in five weeks.

A colt must talented, consistent and adaptable to three different racetracks, as well as being durable enough to remain at a peak level of performance through the most demanding five weeks of his life.

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In the Kentucky Derby at Churchill Downs, he runs 1 1/4 miles, which but for the extremely rare exception is the longest race of his life so far. He then ships to Baltimore for the 1 3/16-mile Preakness at Pimlico two weeks later. Then it's on to New York for the ultimate test three weeks later in the wide, sweeping expanse of Belmont Park's 1 1/2-mile oval.

Considering the rigors of the Triple Crown, Animal Kingdom enters with the significant advantage of being a lightly-raced colt who went into the Derby fresh.

The Graham Motion trainee had not raced since winning the Spiral Stakes at Turfway Park on March 26, making him the first to win the Derby off a six-week layoff since Needles in 1956.

In an even more historic coup, Animal Kingdom is the first since Exterminator in 1918 to win the Roses in only his fifth start. In the last 93 years, the only Derby winner with less previous experience was Big Brown, who won in his fourth race. Except for chronic quarter-cracks, which prompted jockey Ken Desormeaux to pull up Big Brown in the homestretch in the Belmont on June 11, 2008, he certainly would have won the Triple Crown.

Animal Kingdom's race videos   Kentucky Derby (first place), May 7 Spiral Stakes (first place), March 26

Animal Kingdom's sparse campaign is by design, not by necessity like Big Brown's. The brawny, strapping Animal Kingdom has always shaped up like a colt who would be better at three than as a young juvenile. Nevertheless, the raw colt still flashed talent at two for his original trainer Wayne Catalano. After finishing a mightily-troubled second in a deep maiden in his career debut, he came back to romp in a 1 1/8-mile event on Keeneland's Polytrack last fall.

Barry Irwin, the impresario of Team Valor International, then began mapping out a strategy to get his homebred to the classic races. The first item on the agenda was a leisurely winter vacation for the colt, a holiday before getting down to the serious work that lay ahead.

Subsequently transferred to Motion, Animal Kingdom often worked in company with a much more accomplished stablemate, the Breeders' Cup Juvenile Turf hero Pluck, and matched strides with him. Pluck was at that time under consideration for an Irish or French classic, until he developed an injury, so he was quite a sparring partner.

Animal Kingdom returned to action with a barnstorming second in a one-mile turf race at Gulfstream Park, just missing by a head, in a fine comeback that set him up perfectly for the 1 1/8-mile Spiral.

Animal Kingdom's race record points to another key factor supporting his Triple Crown ambitions — his stamina. Unbeaten at 1 1/8 miles and beyond, his two losses were at shorter distances, with troubled trips to boot.

Sired by champion turf horse Leroidesanimaux, an especially brilliant miler, Animal Kingdom inherits his bottomless stamina from his dam, the German-bred Dalicia, who defeated high-class males in her homeland. Dalicia is by the great German champion Acatenango, the winner of seven Group 1 races (the highest class level) at 1 1/2 miles, and an outstanding stamina influence at stud. German bloodlines are generally known for their toughness and soundness, indispensable prerequisites for the Triple Crown.

So if Animal Kingdom passes the initial tests regarding his constitution, the discussion turns to whether he is good enough to win the Triple Crown. This demands a two-part answer, embracing both Animal Kingdom and the state of his opposition.

Little seasoning but mental toughness
First, Animal Kingdom is special for winning the Derby without much seasoning. Even allowing for the changing methods of training, and emphasis toward fewer races, a horse still needs mental maturity and professionalism to cope with the unique hurly-burly of the Derby.

And Animal Kingdom accomplished this in his first try on dirt after racing on turf and Polytrack, thus becoming the first horse to win the Derby in his dirt debut. He appears remarkably indifferent to whatever surface he encounters — another mark of quality.

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Animal Kingdom was also capable of working out the winning trip for himself, no mean accomplishment in a 19-horse field. Although he's a closer, Animal Kingdom doesn't have to drop way out of it early. He has a touch of versatility in allowing his rider to place him in a good spot.

Johnny Velazquez did just that in the Derby, so he didn't fall too far behind the ridiculously slow pace. That ability to make a slight tactical adjustment, as need be, is critical for success in the Triple Crown, where the tempo can vary considerably. The Preakness figures to have a faster pace, the Belmont will probably be a crawl, so Animal Kingdom will have to find his rhythm in the right place for him.

Nehro could be tough challenge at Preakness
As far as his opponents are concerned, we need only recall the past few months of an especially rocky road to the Derby. With several prime contenders derailed by injury, a cavalcade of upsets in the prep races, and finally Uncle Mo's withdrawal because of illness, the 3-year-old division was in total flux by the first Saturday in May.

With a wide-open Derby, an upwardly-mobile colt had the opportunity to advance his claims. Animal Kingdom seized the opportunity in style, rallying powerfully to win with authority.

To be fair, a couple of Derby rivals had excuses, and different kinds of trips might have helped them. Nehro ran a huge race after being wide throughout, and making an arguably premature move to strike the front. The late runner couldn't sustain his momentum in the deep stretch, when he was overwhelmed by the well-timed bid of Animal Kingdom. If Nehro gets a more favorable scenario in their rematch, he can make things interesting.

Beaten Derby favorite Dialed In likewise ran a sneakily good race. After falling much too far back off the dawdling pace in last, he finished his final quarter-mile even faster than Animal Kingdom to finish eighth. With a more favorable pace scenario next time, Dialed In can have a better chance to join the fray.

Still, Animal Kingdom succeeded where they failed, and the onus is on them to turn the tables. New shooters, horses who didn't make it to the Derby, are already lining up to take their chances, but they've got even more to prove. At the moment, Animal Kingdom is wielding legitimate credentials to sweep the Triple Crown.