He will not be in the starting gate around 6:30 p.m. Saturday, but Uncle Mo holds the key to the 142d Kentucky Derby.

Uncle Mo resides at Ashford Stud in Versailles, Ky., about 55 miles from Louisville, and has become one of the leading sires of thoroughbred racehorses in the United States. He is the sire of the Derby favorite, Nyquist, and two other contenders, Outwork and Mo Tom. This is the first crop of his offspring to race, and they took to racing brilliantly, not unlike their father.

Uncle Mo debuted at Saratoga on Aug. 28, 2010, and obliterated a field of maidens by 14½ lengths. He later won the Breeders’ Cup Juvenile and was named 2-year-old champion.

As a 3-year-old in 2011, he won one race and then finished third in the Wood Memorial in preparation for the Kentucky Derby. He was going to be the Derby favorite but he contracted a mysterious ailment that eventually was diagnosed as a rare liver disease, and he had to be scratched.

He raced three more times, finishing a dismal 10th in his final race, the 2011 Breeders’ Cup Classic. He never won at a distance greater than a mile.

We already know that Uncle Mo’s offspring can win at shorter distances and win impressively. What we don’t know is whether they can run at longer, classic distances like the 1¼-mile Derby.

This is one of the reasons many people doubt Nyquist and feel he’s a favorite you can bet against even though he is undefeated in seven races. The negative feelings have cooled somewhat because the other colts haven’t been that impressive in preparing for the Derby.

But one horse whose preparation has been praised by veteran Derby observers is Outwork, who is coming off a front-running victory in the Wood Memorial. Mo Tom, the other Uncle Mo colt, is a late-running sort who seems to find traffic problems easily, and there will be more than enough of those in the Derby. It’s doubtful he can avoid that problem.

Outwork’s victory in the Wood did not produce a particularly fast speed figure, but it was visually impressive as he was ridden hard from the outside post to get the early lead and still had enough to hang on for the victory. Finishing second, however, was Trojan Nation, a horse that has never won. That’s perplexing for what looked like a great victory.

Outwork, who is 15-1, will have to improve to win the Derby, but he can move forward from that Wood performance; 3-year-olds often quickly improve in April and May. The “Uncle Mo distance problem’’ should apply to him, too, unless you look at his dam’s sire, Empire Maker. He won the Belmont Stakes. From that, you take hope that he has enough stamina.

For Nyquist, his dam, Seeking Gabrielle, won only one race and that was at 6 furlongs. Her sire, Forestry, was considered to be at his best at sprint distances but did win at 1 1/16 miles twice.

So both horses have distance pedigrees in their backgrounds and, as we sometimes see in our families, recessive genes can show up.

The pace of the Derby should be moderate, with Danzing Candy leading, followed by Outwork, Nyquist, and possibly Mohaymen (who has been headstrong on the track this week).

A grouping of Gun Runner, Mor Spirit, Destin, and Shagaf should be in the next tier. The late runners who are threats are Exaggerator, Brody’s Cause, Creator, Suddenbreakingnews, Whitmore, Tom’s Ready, My Man Sam, and Majesto, but they will have to hope the early pace is torrid to have any chance.

That’s not likely to happen. These colts aren’t as good as last year’s group, but the running of the race could be similar — a moderate pace with the front-runners and the next-tier horses the biggest threats.

In general, this is a wide-open race, and the results could be unpredictable.

Outwork is ridden by one of the best, John Velazquez. He should find a place near the front but in a good spot, hopefully saving ground — take the lead at the top of stretch and tap into those Empire Maker genes to get to the finish line first.

Prediction: 1. Outwork; 2. Mor Spirit; 3. Nyquist.

Joe Sullivan can be reached at joseph.sullivan@globe.com. Follow him on Twitter @GlobeSullivan