James Crisp, Associated Press GOOD BLOODLINES: La Ville Rouge and her foal run in a paddock yesterday at Mill Ridge farm near Lexington, Ky. The foal is a two-week-old full brother to last year's Kentucky Derby winner Barbaro.

LOUISVILLE, Ky. -- Curlin is undefeated, unchallenged and now he's the favorite for the Kentucky Derby.

And in drawing the No. 2 post for Saturday's race, the imposing chestnut colt even gets to start from the same spot Affirmed did on his way to winning the Triple Crown in 1978 -- the previous horse to do so.

The question is: Can he win it?

"We don't know how good this horse is, but he's just been dominating," Churchill Downs oddsmaker Mike Battaglia said in making the colt a slight 7-2 favorite over 4-1 Street Sense.

Still, Curlin has a few things to overcome.

He didn't compete as a 2-year-old and has run only three races in his career -- though he won them by a combined 28 lengths.

History isn't on his side, either. It has been 125 years since Apollo won after skipping his 2-year-old season, and not since the filly Regret in 1915 has such a lightly seasoned horse worn the blanket of red roses.

Curlin will be ridden by Robby Albarado in a full field of 20 3-year-olds going 1 1/4 miles.

Besides Curlin, trainer Steve Asmussen will saddle Zanjero, a 30-1 shot, who will start outside Curlin.

"They got a friend near each other," he said. "They're going to think they're working together."

Trainer Todd Pletcher will try to end his 0-for-14 skid in the Derby with a record-tying five entries: Any Given Saturday, Circular Quay, Cowtown Cat, Sam P. and Scat Daddy.

"It's a very difficult race to win," he said. "We feel like we got our horses prepared well. Now we need some of the other things to go right."

Street Sense will try to end two of the Derby's longest jinxes: no Breeders' Cup Juvenile winner has ever gone on to win the Derby; no 2-year-old champion has won since Spectacular Bid in 1979.

With Calvin Borel aboard, Street Sense will leave from the No. 7 post for trainer Carl Nafzger, who won the 1990 Derby with Unbridled from the same position.

"Our horse has got a little speed," he said. "He can maneuver and watch what's going on."

The most successful post positions in the Derby's 132-year history have been Nos. 1 and 5, which have produced 12 winners each.

Since the 20-horse rule began in 1984, the race has gone off with a full field twice -- in 2005 when Giacomo won at 50-1 odds and last year when Barbaro won by 6 1/2 lengths.