Authorized is now an odds-on favourite to secure Frankie Dettori a first Epsom Derby success on Saturday but the Italian jockey could end up having to beat the massed ranks of Ballydoyle to do it.

Of the 19-runner field Aidan O'Brien has a massive team of eight horses. They include Michael Kinane's likely mount Archipenko and, significantly, Eagle Mountain, who had been under consideration for Sunday's Prix du Jockey Club at Chantilly, is also now in the firing line for a run at Epsom. "Eagle Mountain is definitely in the picture," O'Brien said. "While he handles fast ground, he also handles an ease."

That ability to handle testing conditions could yet turn out to be the main theme of Derby 2007 and it contributed yesterday to further sustained support for Authorized who won the Racing Post Trophy last year on soft going.

Peter Chapple Hyam's colt is now a 5 to 6 favourite with many firms and fast ground-loving horses like Salford Mill are on the drift. An estimated 34mms of rain fell on Epsom over the weekend and the ground is now officially soft on the Derby track. "I don't think good to firm is a possibility. It would depend on how much rain we see during the week but any amount of dry weather and it will settle down," said the Epsom clerk of the course Andrew Cooper. "I would be thinking there is a good chance of us being somewhere around good to soft on Saturday, and maybe a shade slower on Friday," he added.

O'Brien, a Derby winner in 2001 and 2002 with Galileo and High Chaparral, has run four horses in the race before, including last year when Dylan Thomas was third and Horatio Nelson picked up fatal injuries in the finishing straight.

However, with Authorized dominating the betting and the build-up, Ireland's champion trainer could yet decide to throw even more ammunition at the race. His other Derby options are Acapulco, Admiralofthefleet, Anton Chekhov, Mahler, Soldier Of Fortune and Yellowstone. Ground conditions also look likely to play a part in Friday's Oaks although John Oxx was yesterday leaning towards running Four Sins in the race despite the testing going. "She handled an ease better than we expected when she won at Naas and it would be unusual at Epsom for it to get proper soft. Obviously we will have to keep an eye on it. If it is on the soft side of good, I imagine the plan will still be to run but if it does get very soft, then we may have to think again," the Curragh trainer said.

At Ballinrobe this evening the champion jockey Declan McDonogh looks to have reasonable chances of a double. Carpetcall ran a good third to Asafa at Navan over a month ago and crucially has a good draw for the opening handicap while Misty Island, a rare flat starter for the in-form Adrian Maguire, won't mind any ease in the ground for the second nine-furlong handicap.

Arigna and Connemara Rose renew hostilities from Roscommon in the handicap chase and with the latter 2lb better off and with Ruby Walsh on board, that might be enough to swing it.