LOUISVILLE, Ky. — There's a curiosity about Big Brown in the Kentucky Derby. Is he really as good as trainer Rick Dutrow Jr. has boasted? Is he the rare favorite who will win? Can he defy tradition by winning off just two prep races?

Those questions and more will be answered Saturday when a full 20-horse field, including filly Eight Belles, runs 1Z\v miles in America's greatest race.

The way Dutrow talked leading up to the 134th Derby, there's Big Brown and a bunch of also-rans in the race.

"Who knows? I don't think anyone really knows except Dutrow," said Barclay Tagg, who will saddle Big Truck and Tale of Ekati in pursuit of his second Derby win. "He at least says what he thinks; I'm not knocking him for it. He seems to know what's going on better than I do."

Dutrow even dissed Eight Belles, who is 4-for-4 this year.

"I can't imagine there's a filly in this world that can beat Big Brown," he said.

Big Brown is the 3-1 morning-line favorite for the $2 million Derby, having won all three of his races by a combined 29 lengths. He didn't race as a 2-year-old, challenging the notion that young colts need plenty of seasoning before trying the Derby.

Favorites rarely win the Derby, either; only three have done so since Spectacular Bid in 1979, including Street Sense last year.

Another challenge facing Big Brown is overcoming the No. 20 post on the far outside, something only 1929 winner Clyde Van Dusen accomplished. But Big Brown scored a five-length victory in the Florida Derby leaving from the outside post.

Dutrow has been over-the-top with his confidence, touting Big Brown as the best and fastest horse in the race.

"I just can't wait until (Saturday) when they load him in the gate. He's a dream come true, seems like he was born for this track," he said. "I'm sitting on go here, we're ready."

A dominant win by Big Brown would renew excitement about a possible Triple Crown champion for the first time since Affirmed swept the Derby, Preakness and Belmont Stakes 30 years ago.

"We could get a standout horse after the Derby, but right now it's hard to say one of them has star quality," said Hall of Fame trainer D. Wayne Lukas, a four-time Derby winner. "It's been a little upside down this year."