The colt was last year's 2-year-old champion and a favorite for the Kentucky Derby until he came down with a mysterious illness. He was scratched from the Run for the Roses while owner Mike Repole and trainer Todd Pletcher sought explanations.
Eventually, the Indian Charlie colt was diagnosed with a liver ailment and put on the road to recovery. He returned to the races in the 7-furlong King's Bishop at Saratoga and was beaten by a nose after leading all the way. Then he won easily in the 1-mile Kelso Handicap on the Belmont Park mud Oct. 1.
Now, off those two efforts, he is being asked to go 1 1/4 miles -- a distance he's never tried -- against more experienced opposition.
In addition, his final workout on Sunday, 5 furlongs in 1:01.19, wasn't sparklingly fast, prompting some published speculation Uncle Mo is not really back to the level of ability he showed last year.
"What disturbs me about everything being said about Uncle Mo's work was, it was a good work," Pletcher said Thursday morning at Churchill Downs, where the 15 Breeders' Cup World Championship races will run Friday and Saturday.
Pletcher said many trainers tend to be caught up in the excitement of the big week and train their horses faster than normal. He endeavors, he said, to maintain a constant level of training, which only seems slow by comparison.
Pletcher also said he considered running Uncle Mo in the 1 1/8-mile Pennsylvania Derby rather than the shorter Kelso but opted to keep him at home at Belmont Park. "I feel like we've gotten as much foundation as we could get," he said.
Repole added, "When you have a horse as good as Uncle Mo, he deserves a chance. He could win at a mile. He can win at a mile and a quarter."
Among those facing Uncle Mo and his stablemate, Stay Thirsty, in the Classic is the former Australian champion So You Think, who has been campaigning this year in the British Isles under the tutelage of Aidan O'Brien.
So You Think, a 5-year-old, comes into the Classic off a second-place finish in the Champion Stakes at Ascot and a fourth in the Prix de l'Arc de Triomphe at Longchamp -- beats that O'Brien excused on pace and traffic grounds.
"We're very happy with the horse," the Irish conditioner said. "Obviously, we've got beat in a lot of Classics in the past. You need a very experienced horse that can get the distance. This is a seasoned horse. He seems tactically quick."
O'Brien has had four winners from 63 Breeders' Cup starters but never a winner in 11 tries in the Classic. Among his Classic also-rans are such super horses as Galileo, Giant's Causeway, Rip Van Winkle and Henry the Navigator.
"We've got so many good horses beaten in his race," he said, "I wouldn't even dream about winning it. But if I ever do, it would be incredible."
The lone filly in the field, Havre de Grace, already has beaten males this year in the Woodward and trainer Larry Jones said he hopes he has put her in a position where, with a win in the Classic, she could be the third straight female U.S. Horse of the Year, following Zenyatta and Rachel Alexandra.
"We said halfway through the year that we wanted to put her in a position where if she was good enough, she could be considered for Horse of the Year honors," he said. "When we did take on the boys in the Woodward, it sure looked like that was the right choice. She sure has earned her chance in here."
The Classic, with a field of 13, winds up the two days of Championship racing under the twin spires. Good weather is forecast after Friday rains. The races will be televised in the United States on ABC, ESPN and ESPN2 and broadcast on radio by Horse Racing Radio Network.
Friday's six races start with the first-ever running of the Juvenile Sprint, which drew a field of nine, then continue with five races restricted to fillies and mares.
The Friday card wraps up with the $2 million Ladies' Classic, with 10 fillies and mares going 9 furlongs on the main track. Early in the year, the race shaped up as a showdown between Havre de Grace and Blind Luck. But Blind Luck is done for the year after a poor performance in California in her last race and Havre de Grace is pursuing the richer target.
That, however, leaves an intriguing showdown among 3-year-old fillies, including Kentucky Oaks winner Plum Pretty, Coaching Club American Oaks victor It's Tricky and Alabama winner Royal Delta.
Plum Pretty has only one victory in four starts since her Kentucky Oaks triumph at Churchill Downs and trainer Bob Baffert said Thursday the Medaglia d'Oro filly "knows she's back. She looked good out there," the silver-haired trainer said. "She loves the track. She gets along over it really well. The Kentucky Oaks was a long time ago. But if she can repeat the race she ran last time, she'll have a very good chance."
Saturday's seven Championship races, besides the Classic, include the $2 million Mile, in which French-trained Goldikova will try to become the first horse to win four Breeders' Cup races. She has captured the past three runnings of the Mile.
Elsewhere, both in the United States and overseas, there is little racing action of note.
Aqueduct kicks off the long winter in New York with the $150,000, Grade II Red Smith Handicap at 11 furlongs on the turf Saturday.
Santa Anita has the $150,000, Grade II Las Palmas on Sunday with fillies and mares going 1 mile on the grass.
And at Flemington in Australia, the spring festival continues with a flurry of graded races.