Hunting Horn, third in the Group 3 Classic Trial at Sandown Park on April 27, will be a lukewarm favorite to give trainer Aidan O’Brien and jockey Ryan Moore a sixth successive win in Wednesday’s Group 3 Chester Vase at Chester Racecourse in England. The $136,000 Chester Vase is run at about 1 1/2 miles on turf and is a key prep for the English Derby at Epsom Racecourse on June 2. Moore has ridden Hunting Horn in both of the colt’s starts this year – a win in a maiden race at Naas, Ireland, on April 13, and in the Classic Trial. Hunting Horn finished 1 1/4 lengths behind Sevenna Star in the Classic Trial at 1 1 /4 miles on turf. The Chester Vase drew a field of 10. O’Brien also runs Flag of Honour, who was third in the Group 3 Prix Noailles at Longchamp in Paris on April 15; and Family Tree, a maiden race winner in his only start at Gowran Park in Ireland last September. Ispolini, trained by Charlie Appleby, and Young Rascal, trained by William Haggas, are leading threats to Hunting Horn. Ispolini was second by a short head in the Classic Trial at Sandown. Young Rascal won a maiden race at 1 3/8 miles on turf in his second career start at Newbury Racecourse on April 21. O’Brien has won the Chester Vase eight times, beginning with Soldier of Fortune in 2007. Moore has won the race seven times, beginning with Doctor Fremantle in 2008. Together, O’Brien and Moore have won the Chester Vase with Treasure Beach (2011), Ruler Of the World (2013), Orchestra (2014), Hans Holbein (2015), U S Army Ranger (2016), and Venice Beach (2017).