LOUISVILLE, Ky. (AP) -The Breeders' Cup began with fists flying in the winner's circle.

The mayhem was just starting.

Jockeys brawled and long shots dominated on a wild opening day, capped by Unrivaled Belle's victory in the $2 million Ladies' Classic under the lights Friday at Churchill Downs.

Unrivaled Belle ran 1 1-8 miles in 1:50.04, winning by 1 3/4 lengths over 3-2 favorite Blind Luck in front of 41,614.

Jockeys Calvin Borel and Javier Castellano traded punches after the first Breeders' Cup race, with an enraged Borel needing to be restrained. He was furious about a move in tight quarters by Castellano.

Shared Account scored the second-biggest upset in the event's 27-year history, winning the $2 million Filly & Mare Turf at 46-1 odds on a gray and chilly day.

Celebrity chef Bobby Flay earned his first Breeders' Cup victory as owner of More Than Real in the $1 million Juvenile Fillies Turf.

American horses won all of the six races. No jockey or trainer won more than one race on a day where horses and riders got around safely.

Off the track, though, was a stunningly different story.

The genteel atmosphere of the Breeders' Cup - well-dressed fans, wealthy owners and gorgeous horses worth millions - was jolted when Borel and the lesser known Castellano tangled in the winner's circle after the opening race.

Borel charged Castellano shortly after the $500,000 Marathon, angry over a mid-race move in traffic that endangered Borel and fellow rider Martin Garcia.

Borel, the usually smiling three-time winner of the Kentucky Derby, turned livid during the fight that went on for several minutes in front of startled onlookers. His eyes bulged and the veins in his forehead stood out as he resisted being held back.

Eventually, his wife and brother each took one of his arms and marched Borel back to the jockeys' room, where further scuffling broke out between the two riders. He later apologized and rode in two other races, but didn't win.

The races went off without Zenyatta, who was back in her barn waiting to defend her title Saturday in the $5 million Classic against the boys. She will put her 19-0 winning streak on the line in the 1 1/4-mile race, the richest in North America.

The two-day world championships were back at Churchill Downs for a record seventh time, and the first in three years to be run on dirt. The event was on the synthetic track at Santa Anita the last two years.

The lights dotting the home of the Kentucky Derby were turned on before daylight faded. The dirt oval was brightly lit for the Ladies' Classic that went off at 7:35 p.m.

``I don't think the horses know its nighttime out there,'' winning jockey Kent Desormeaux said. ``It is so bright. Everyone can see where they're going. It's safe.''

Under Desormeaux, Unrivaled Belle was fifth much of the way before making a four-wide move on the final turn and taking charge at the top of the stretch. She paid $17, $5.80 and $4.20. The gray filly is owned by Gary Seidler and Peter Vegso, publishers of the ``Chicken Soup for the Soul'' series of motivational books.

``She left them for dead leaving the three-eighths pole. I mean, it was over,'' Hall of Fame trainer Bill Mott said.

Blind Luck ran next-to-last until rallying with three-eighths of a mile to go under Joel Rosario. She returned $3.20 and $2.40. Havre de Grace paid $4 to show.

After the fight and inquiries into the results of the first two races, things settled down until ending on a controversial note in the Ladies' Classic.

Life At Ten, the 7-2 second choice, finished last, and jockey John Velazquez later said the filly wasn't warming up well before the race. She broke sluggishly, quickly dropped back and lost contact with the rest of the field after a half-mile.

``She seemed OK,'' Velazquez said. ``She never put in any effort whatsoever. I tried to warm her up and wake her up, and she just never felt like running.''

Trainer Todd Pletcher said Life At Ten was ``abnormally quiet, almost sedated-like'' while being saddled. He speculated the 5-year-old mare might have had an allergic reaction to Lasix, an anti-bleeding medication legal in Kentucky.

``It's a tough situation for Johnny to be in,'' Pletcher said. ``He asked the vets to look at her and she was moving soundly but clearly she probably should not have run. Of all the horses we've run over here today, none were doing better than her.''

Pletcher's other entry Malibu Prayer finished 10th.

Life At Ten is owned by Candy DeBartolo, the wife of former San Francisco 49ers owner Ed DeBartolo Jr.

In the other races:

-Eldaafer won the 1 3/4-mile Marathon by 1 3/4 lengths for Velazquez and trainer Diane Alvarado. He paid $23.20 to win.

-Flay's horse More Than Real won the $1 million Juvenile Fillies Turf by two lengths under Garrett Gomez and paid $29.20. It was Pletcher's lone win on the day.

-Dubai Majestry won the $1 million Filly & Mare Sprint by 2 1/4 lengths, giving jockey Jamie Theriot his first BC title. She paid $19.20.

-Awesome Feather won the $2 million Juvenile Fillies by 2 1/4 lengths, making jockey Jeffrey Sanchez and trainer Stanley Gold winners in their BC debuts. She paid $10.40.

-Shared Account and jockey Edgar Prado won the $2 million Filly & Mare Turf by a neck in the day's closest race. She paid $94.