New York: Favourite Big Brown, unbeaten in three career starts, faces a tough test in the Kentucky Derby after drawing the 20th post position on Wednesday for tomorrow's opening Triple Crown race for three-year-olds.

Despite starting from the extreme outside in the crowded 20-horse field, Big Brown was installed as a 3-1 early favourite for the mile and a quarter run at Churchill Downs.

Big Brown, whose most recent win came from the far outside in last month's Florida Derby, had the 16th pick of the draw whose selection order was previously decided.

Colonel John, starting from the 10th berth, was the early second choice at 4-1, followed by Pyro at 6-1, going off from the ninth post position.

Contenders Visionaire and Eight Bells were also slotted into favourable middle berths for the first jewel of the Triple Crown, which continues with the Preakness and Belmont Stakes.

Visionaire chose first in the draw and the three-times winner took the eighth starting spot.

Eight Belles, aiming to become only the fourth filly to win the Kentucky Derby after victories in her last four races, will start in the fifth spot after selecting sixth in the draw held in Louisville.