Could Nelson Start Favourite? Such is the power of the ‘Fallon Factor’ that leading bookmakers believe there is “every chance” Horatio Nelson could start favourite for the Vodafone Derby.Former champion Kieren Fallon takes the mount on Aidan O’Brien’s charge, who dazzled in a piece of work at Ballydoyle earlier in the week, at Epsom on Saturday.The news left the layers quaking and David Stevens, spokesman for Coral, who have already been forced to cut his price into 4-1 from double figures, said “Such is the faith that punters have in Fallon, there must now be every chance that his mount will be sent off as favourite on Saturday.The son of Danehill was also cut to 9-2 from 5s by Ladbrokes, whose David Williams said: “We’re still laying Horatio Nelson whereas support for the French favourite has begun to stall. We’ve eased Visindar for the first time as the Fallon bandwagon gathers pace.”Michael Kinane will ride Dante winner Septimus and Johnny Murtagh will partner Derrinstown Derby Trial winner Dylan Thomas.The fourth O’Brien representative, Mountain, is still without a rider at this stage.Hala Bek was last night set to be handed the green light for his challenge.The Michael Jarvis-trained son of Halling has been prominent in betting lists for the blue riband since running out an impressive winner of his maiden at Newbury in April.He missed his next intended engagement in the Dante Stakes at York after an unsatisfactory scope.But he has progressed since recovering and Jarvis has expressed himself satisfied with Hala Bek’s big-race preparation.“The position is that he worked nicely this morning and we are happy with the horse,” Jarvis said.“I spoke to Aziz Merza, Sheikh Ahmed’s racing manager, and he will be speaking with Sheikh Ahmed because he is abroad.“We’ve said that we are happy to run the horse and we are just waiting for the go-ahead.“The work he’s done, he’s done satisfactorily and he looks well.“Obviously he’s inexperienced but he’s always been pretty straightforward, which should make it a bit simpler on Saturday.”But one horse that will not be seen hurtling around Tattenham Corner is the Barry Hills-trained Olympian Odyssey.He is now set to tackle the French Derby at Chantilly over an extended ten furlongs on Sunday.Owner Bill Gredley had repeatedly expressed stamina doubts for his 2000 Guineas third and it looks likely that his head has ruled his heart.“It has been decided that Olympian Odyssey will run in the French Derby and Jamie Spencer will ride,” a stable spokesperson told PA Sport.“Obviously Mr Gredley has until 10am tomorrow to make a final decision but, in all probability, he will go for the French Derby.”The news leaves champion jockey Spencer with a frantic last minute race for a ride, one he looks like losing according to his agent, Andrew Sheret.“At this stage Jamie doesn’t have a ride,” said Sheret. “It looks like everything is booked up unfortunately.“Unless something unexpected happens between now and declaration time he will be without a ride.”One man who has landed a plum mount is Spencer’s main rival for the title, Robert Winston.His services have been snapped up for the Sir Michael Stoute-trained Papal Bull, who was last seen winning the Chester Vase in impressive fashion.? PA Sport