LOUISVILLE, Ky. (AP) -A jockey brawl in the winner's circle and long-shot victories made for a wild opening day at the Breeders' Cup, 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.

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 him back to the jockeys' room. He later rode in two other races and 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 light poles 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.

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 after 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.

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 which is legal in Kentucky.

``Clearly, she probably should not have run,'' said Pletcher, whose other horse Malibu Prayer finished 10th.

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