John Murtagh has been entrusted with the hot seat on Dylan Thomas in Saturday's King George VI and Queen Elizabeth Diamond Stakes, where the ante-post favourite and his stable companion Scorpion look set to face just a handful of opposition for one of British racing's top prizes.
Only eight horses remain in the King George after yesterday's forfeit stage, and they include O'Brien's consistent three-year-old Yellowstone, who is the sole representative of the classic generation remaining in the race.
But O'Brien all but ruled Yellowstone out yesterday, and said: "It looks like Dylan Thomas and Scorpion will probably run. Mick (Kinane) will ride Scorpion and we have decided that Johnny will be on Dylan Thomas."
The latter is an odds-on favourite in many ante-post lists for what is traditionally the midsummer all-aged highlight in Britain, but which has already been labelled "substandard" in some quarters after the expected defections of the Derby winner Authorized and the Irish Derby hero Soldier Of Fortune.
Murtagh, however, will be hoping it is fourth time lucky for him on Dylan Thomas. He was narrowly beaten into third in last year's Epsom Derby on the colt, and was beaten twice on him as a two-year-old.
But Murtagh was a late sub for the injured Kieren Fallon when Peeping Fawn won the Irish Oaks this month, and significantly his record includes a King George success aboard Alamshar in 2003.
Ranged against the Irish pair will be the Michael Stoute-trained Maraahel, a double Hardwicke Stakes winner but still searching for an elusive first Group One success, as well as Laverock, who will represent Godolphin.
The international element will be added to by the appearance of the star German runner Prince Flori, while the hugely popular stayer, Sergeant Cecil, is also a likely runner.
Dylan Thomas is an 11 to 10 chance with Coral for the King George, while Scorpion is rated his main danger at 4 to 1. Maraahel is 5 to 1 next best.
Yellowstone also features among six O'Brien-trained entries for Saturday evening's Meld Stakes at Leopardstown, a Group Three event for which David Wachman also has three options. The former Derrinstown Trail winner Fracas is among the trio, as is Cougar Bay.
Saturday's other Group Three is the Tyros Stakes for two-year-olds, a race won by the juvenile champion Teofilo last year.
His stable companion New Approach, an impressive winner on his debut at the Curragh, is one of 11 hopefuls for the seven-furlong event, which has also attracted the unbeaten Bruges from David Myerscough's yard.
Fifteen remain in the Listed Sweet Mimosa Stakes, including Jessica Harrington's Moone Cross, who was a length-and-a-half runner-up to Haatef at Fairyhouse on Sunday.
The ground at Leopardstown is soft with soft to heavy patches, and the forecast is unsettled.
That won't be good news for Charlie Swan, who has warned that his highly rated Emmpat is not a certain starter in next week's Galway Hurdle.
"It would have to be very good ground for him to run," the trainer said. "I haven't got any other major plans for him. He may go for a couple of races on the flat wherever the ground is decent."
The going at Ballybrit is also a worry for Liam Burke, who has the fancied Sir Frederick ready to run in the William Hill Plate.
"We're definitely planning to run, but I just hope it is not too soft. But I believe the forecast isn't good. He really needs good ground," Burke said.
The former high-class flat racer Nasafar is an interesting runner in the maiden hurdle at Ballinrobe this evening, especially since the ex-John Oxx runner was beaten 97 lengths on his only jumps start to date last December.
But he was rated as high as 97 for Oxx last year, and he ran an okay fourth behind Sorolla at Naas recently, which suggests he is worth another shot.
A feature of the last few weeks has been the form shown by Jim Gorman's string, and no one could deny the consistent Desert Rat is worth a victory in the opening nine-furlong handicap.
Jeux Sont Faits was an expensive failure on her last start at Wexford, but her second to Mamlook at the same track before that would give Dermot Weld's filly a shout in the mile-and-a-half maiden, where the 84-rated Davidii looks to set the standard.
