Oddsmakers at online sportsbooks have Big Brown as a big favorite to become the first thoroughbred in 30 years to win horse racing’s Triple Crown.

Big Brown, the Kentucky Derby and Preakness Stakes winner, is at 2-7 odds at Bodog and 1-3 at MySportsbook.com to win the Belmont Stakes on June 7, the third jewel in the Triple Crown.

Big Brown would be the first Triple Crown winner since Affirmed in 1978. It’s the longest dry spell since Secretariat snapped a 25 year drought in 1973.

The horse had just three races before the Derby, but blew away the competition in all three of those races, and has done the same in the first two jewels of the Triple Crown. Big Brown is the first three-year-old since Smarty Jones in 2004 to go into the Belmont Stakes with a chance to sweep the three races.

But many expect Big Brown to face its stiffest competition yet in the Belmont, specifically from Casino Drive, the next closest horse at 9-2. Casino Drive, which did not race in the Derby or the Preakness, won the Peter Pan Stakes. He is a half-brother to Jazil and Rags to Riches, the winners of the last two Belmont Stakes.

Other horses in the top five are Denis of Cork (12-1), Tale of Ekati (20-1) and Behindthebar (25-1).

Denis of Cork, which finished third at Churchill Downs, hails from the first crop of multiple Grade 1 hero Harlan's Holiday, a grandson of the mighty Storm Cat. An earner of more than $3.6 million in the course of his career, Harlan's Holiday was a major player on the 2002 Kentucky Derby trail.

The Belmont Stakes takes place June 7 at 6 pm ET on ABC.