LOUISVILLE, Ky. -- Upsets ruled on the second day of the Breeders' Cup, with Afleet Again pulling off the biggest surprise at 41-1 odds in the Marathon and 18-year-old Irishman Joseph O'Brien winning the Turf for his father-trainer Aidan O'Brien on Saturday.
Later, Uncle Mo was the early favorite for the $5 million Classic, with filly Havre de Grace taking on the boys in the showcase race of the two-day world championships.
Goldikova was poised to go for her record fourth consecutive win in the $2 million Mile. Union Rags was the early 2-1 choice in the Juvenile, with the winner likely becoming the early favorite for the Kentucky Derby.
In the Marathon, Afleet Again rallied to win by 2 1/4 lengths under Cornelio Velasquez. He paid $85.20.
The younger O'Brien was aboard 6-1 longshot St Nicholas Abbey, who won the $3 million Turf by 2 1/4 lengths, making him the youngest jockey to win in the 28-year history of the Breeders' Cup. The 4-year-old colt from Ireland paid $15.60 to win.
At 6-feet, O'Brien isn't expected to have a long career in flat racing. As he gets older, his height and weight gain likely will force him to change to steeplechasing.
"It's over this world," O'Brien said about helping his father win his second race of the day. They embraced in the winner's circle.
"Wonderful race. Incredible," Aidan O'Brien said. "What can I say? He's an amazing rider."
Joseph O'Brien has been part of family trips to the Breeders' Cup since he was a child. He rode his first winner in May 2009, and earlier this year scored his first victory in a prestigious Group 1 race.
"My heart was going 100 miles an hour," his mother, Anne-Marie O'Brien, said. "I could hardly stand up I was so nervous."
St Nicholas Abbey's victory was the second of the day for Derrick Smith, Susan Magnier and Michael Tabor, who won the Juvenile Turf with Wrote.
The Marathon was marred by the failure of 3-1 favorite A.U. Miner to finish, along with Meeznah.
Jockey Calvin Borel pulled up A.U. Miner, who fractured the sesimoid bone in his right front leg. Meeznah didn't finish because of fatigue.
The on-call veterinarian said A.U. Miner was set to have lifesaving surgery next week in Lexington. Dr. Wayne McIlwraith said 60 to 70 percent of horses having such surgery do well.
Ireland-bred Wrote won the $1 million Juvenile Turf by 2 1/4 lengths, the first victory by a European-based horse during the weekend. The 12-1 shot paid $25.20 to win for trainer O'Brien.
Hall of Fame jockey Mike Smith guided Amazombie to a neck victory in the $1.5 million Sprint at 7-1 odds. Smith earned his 14th Breeders' Cup win, leaving him one behind the record set by retired jockey Jerry Bailey. The 5-year-old gelding paid $17.80 to win.
Order was restored in the $1 million Turf Sprint, with 2-1 favorite Regally Ready winning by 1 1/2 lengths. He ran five furlongs on the turf in 56.48 seconds. Trainer Steve Asmussen and jockey Corey Nakatani earned their second wins of the weekend, having taken the Juvenile Fillies with My Miss Aurelia on Friday.