Champion juvenile Nyquist established himself as the hot favorite for the Kentucky Derby with his victory in the Grade 1 Florida Derby April 2 at Gulfstream Park, and when his racing days are done, the bold-looking son of top young sire Uncle Mo (by Indian Charlie) will take a place at Darley’s stallion complex at Jonabell in Lexington, Ky.

Nyquist and his sire are the best representatives of a stallion line that until the 1980s was scarcely represented here in the States. This is the sub-branch of Nasrullah through Grey Sovereign and his sons.

For so long, there was no reason to look around for Nasrullah stallions to import. The tempestuous son of Nearco was a hot ticket for the classics in 1943, but his attitude about racing and gadding about on Newmarket Heath got the better of the dark brown horse.

Phil Bull, in the 1943 Timeform annual, variously described Nasrullah with terms like “bad temper,” “mulish antics,” “wayward,” and so forth. Nasrullah deserved them because the striking colt would show exceptional ability, then throw away the race because he could.

Winner of the Champion Stakes in his final start, Nasrullah went to stud in 1944, had his first foals in 1945, and 70 years ago had the first yearlings available that would revolutionize racing in America and, to a lesser extent, in Europe.

Nasrullah sired top-class horses from the start, and when A.B. “Bull” Hancock put together a syndicate to purchase Nasrullah in 1950 and bring him to Claiborne Farm in Kentucky, he scored a massive coup for American breeding.

In the stallion’s first crop came Horse of the Year, Preakness, and Belmont Stakes winner Nashua and in the third came Horse of the Year and Preakness winner Bold Ruler. There were scores of other top sons and daughters, as well.

At stud, Bold Ruler outperformed Nashua, as well as every other stallion in the world. With Bold Ruler, his numerous sons, Nashua and a few of his good sons, Never Bend, Jaipur, and others, there was no rush to add to the Nasrullah sons and strains already available to American breeders.

Then the unthinkable happened, and the great majority of the Nasrullah lines died out. This is the norm with stallion lines, but the pervasiveness of Nasrullah had made him seem unshakeable from his peerless perch in the breeding hierarchy.

Even now, the premier male-line branch of Nasrullah comes through Bold Ruler and is best seen today in Triple Crown Seattle Slew, his champion son A.P. Indy, sons of his such as Malibu Moon, Mineshaft, and Pulpit, and through the latter’s son, leading sire Tapit.

There are other branches, including the Red God twig that comes to us through Blushing Groom. This group of sires continues to be available, if not pervasive in the breed.

And the other increasingly important branch of Nasrullah comes to us through Grey Sovereign, a gray horse born in 1948 from one of the latter crops by his sire overseas. A talented racehorse, Grey Sovereign won the Richmond Stakes, was second in the Nunthorpe, third in the Breeders’ Produce Stakes.

The colt indicated that he had considerable ability, more than he was willing to show consistently, and Timeform marked him with its dreaded squiggle as an unreliable proposition for the betting man.

The world did not beat a path to his stud barn, but Grey Sovereign proved a good sire from the beginning. His offspring had speed, they were more reliable than their sire, and some of them stayed a mile or a bit more.

Grey Sovereign was the leading sire of 2-year-olds in England in 1959 and 1961, the leader in France in 1967. One of his leading representatives was another gray, the quick colt Fortino, who won the Prix de l’Abbaye in a display of speed and class.

Fortino did not make an immediate mark as a sire, was exported to Japan in 1969, and left behind a 2-year-old Irish-bred gray colt who became famous as a racer and a sire known as Caro.

Caro won a half-dozen races, including the Poule d’Essai des Poulains (on the disqualification of Faraway Son), Prix Ganay, Prix d’Ispahan, Prix Dollar, was second in the Eclipse Stakes, third in the Prix du Jockey Club, fourth in the Arc. A very high-class performer from eight to 12 furlongs, Caro was not the greatest racehorse of his time, which would have been either Mill Reef or Brigadier Gerard, but Caro proved himself an exceptional stallion.

Both at stud in France and in Kentucky, Caro sired oceans of class and classic ability on turf and dirt. His best-known performer was doubtless Kentucky Derby winner Winning Colors, but he also sired Madelia (Prix de Diane), Crystal Palace (Prix du Jockey Club), Cozzene (Breeders’ Cup Mile), With Approval (Queen’s Plate), Golden Pheasant (Arlington Million), Tejano (Hollywood Futurity), Dr. Carter (Remsen), and Siberian Express (Prix Morny at 2, Poule d’Essai des Poulains at 3).

The latter became the sire of In Excess, a horse of razor-sharp speed over dirt tracks who went on a tear of major victories that included the Metropolitan Handicap, Suburban, Whitney, and Woodward. A horse of exceptional ability, In Excess went to stud in California and stood for a fee of $5,000.

By far the greatest of his offspring was the towering bay Indian Charlie, who was unbeaten till finishing third in the Kentucky Derby and never ran again. From the first crop of In Excess, Indian Charlie was a major talent, and he sired numerous top performers. His stock could be good juveniles or good older horses.

And the best of Indian Charlie’s sons at stud is clearly champion Uncle Mo. He is writing a new chapter in the book of the Nasrullah line, and we get to watch it unfold page by page.