The Triple Crown has not always had the same format. In 1919, when Sir Barton won what would not be regularly termed the Triple Crown until 1930, the 3-year-old won the Kentucky Derby on May 10, the Preakness on May 14 and the Belmont Stakes on June 11, with a win in the May 24 Withers thrown in for good measure. The distances for the Preakness and Belmont were different from today's.

When Gallant Fox won the Triple Crown in 1930, the Preakness was run before the Derby, but the distances were what they are now.

When Omaha (1935), War Admiral (1937), Whirlaway (1941), Count Fleet (1943), and Assault (1946) won the Triple Crown, the Preakness was just one week after the Derby. In 1948, Citation  had two weeks from the Derby to the Preakness, but his connections could not wait an entire four weeks for the Belmont Stakes, so they had Citation stop at Garden State Park to win the Jersey Derby in between the Preakness and Belmont.

So, the legendary Secretariat (1973) was the first horse to win the Triple Crown with the modern format: Derby on the first Saturday in May; Preakness, two weeks later; Belmont, three weeks after the Preakness. After Seattle Slew (1977) and Affirmed (1978) won it, the Triple Crown started to look impossible — until American Pharoah (2015).

Now, in Saturday's Belmont Stakes, Justify has a chance to be only the second horse to do what Slew did — win the Triple Crown while unbeaten — and the first to win it without racing as a 2-year-old.

Since Slew, only Smarty Jones (2004) and Big Brown (2008) had a chance to win the Triple Crown while perfect. Smarty, who was hassled early by premature moves from horses taken out of their best running styles, deserved to win. Still, Kent Desormeaux's tentative ride on Big Brown — the jockey pulled up the uninjured horse in the stretch — was baffling.

"He's just breathing fire out there,'' Justify's assistant trainer, Jimmy Barnes, said last Friday, after Justify's daily gallop at Churchill Downs.

In videos of the gallops and the two workouts since the Preakness, Justify did not look like a horse that just ran very difficult races in the Derby and Preakness. The massive colt has not lost any weight (still 1,270 pounds). His movements remain incredibly smooth; his stride, impossibly long.

"He's a monster,'' said Dale Romans, the all-time leading trainer at Churchill Downs. "I mean, he's out there; you can just tell that he is a special horse, and I think he's looked really good after the Preakness.''

In his five races, Justify has finished in front of 40 horses, including a few more than once. In the Belmont Stakes, he will need to finish in front of nine more to become the 13th Triple Crown winner.

If that happens, trainer Bob Baffert will win his record 15th Triple Crown race and become just the second trainer to win the Triple Crown twice, after Pharoah won three years ago. Sunny Jim Fitzsimmons won with Gallant Fox and Omaha, a son of Gallant Fox.

"He's the best horse trainer in America, and he always puts his horses first,'' Romans said of Baffert.

American Pharoah had a minor injury before the 2014 Breeders' Cup. As Romans pointed out, Baffert could have run him. He didn't, though, and was rewarded with a horse that won the Triple Crown the next spring.

"We're quietly optimistic that we can hopefully do it again,'' Baffert said. "But I'm a realist. I don't believe it until I see it.''

He almost saw it twice before he finally saw it. Incredibly, Baffert could be going for his fourth Triple Crown. Silver Charm (1997) lost the Belmont by three-quarters of a length, and Real Quiet (1998) lost by a nose.

"Let's see if he can do it," Baffert said of Justify. "He came out of nowhere, and now he's picking up steam.''

Baffert could have been describing his younger self and his 2018 self. The one-time quarterhorse trainer has been a serious player on the Triple Crown scene for two decades. He won his first eight Triple Crown races from 1997 to 2002. Then, he cooled off. Now, he is scorching — another Belmont Stakes win away from a legacy all his own.