Every time Aidan O'Brien holds court on his favourite topic of the moment, an involuntary shudder must pass through Kieren Fallon. Whatever comeback hopes Fallon may have for when his latest ban expires next August, O'Brien's repeated and unstinting praise of Johnny Murtagh makes it tacitly plain that he should not plan on returning to Ballydoyle.

Murtagh will seek his twelfth group one victory of the season on Duke Of Marmalade in the King George at Ascot on Saturday. While he expresses his own gratitude for the chance to ride the most powerful team of horses in Europe, O'Brien insists that his jockey must take credit for the yard's phenomenal success.

After Murtagh's masterclass on Mount Nelson in the Coral-Eclipse Stakes, O'Brien said: “He's an unbelievably special person and I can't tell you the difference it makes having him around.”

Yesterday, with another landmark race approaching, he went further. “The difference he's made has been unbelievable. Everyone sees it, in his work and in how he treats people. He was always a great rider, a great fellow, but now he has the wisdom and experience of age. I can't say enough about him.”

He can, however, probably say more than enough for Fallon's liking, for every reference to the transformation wrought under Murtagh can be construed as a detraction of his predecessor. It is not entirely clear how O'Brien and his Coolmore owners intended to proceed with Fallon after the collapse of his Old Bailey trial last December. Within hours, such decisions were rendered unnecessary by confirmation of another failed drug test in France.

The evident need for a stable jockey made Murtagh's appointment inevitable but it was done with apparent relief. The trainer had long since despaired of his rider's propensity for self-destruction but now the patience of the bosses - John Magnier, Michael Tabor and Derrick Smith - had also expired.

Since then, it is clear that the relationship between O'Brien and Murtagh is of an order never achieved between the trainer and Fallon. In truth, it was never this good when Mick Kinane was at Ballydoyle, either. Kinane and O'Brien were businesslike but never close. With Murtagh, it is a mutual admiration society.

Murtagh's own struggles with addiction - in his case to alcohol - have been well-chronicled and his conquering of the demons stands as an example to all, none more poignantly than Fallon. Whether the troubled soul of the most effective jockey of his generation can respond to the challenge, only time will tell.

Fallon continues to ride work for Sir Michael Stoute but has closed down the website on which he promised, quite possibly to the trainer's distaste, personal progress reports on the stable's horses. Meanwhile, Fallon's trial will be a central feature when Panorama screens its second documentary on racing corruption next Wednesday.

By coincidence, the programme goes out on the evening of the Sussex Stakes at Goodwood. By the time it starts, Duke Of Marmalade, Mastercraftsman (in the Phoenix Stakes) and Henrythenavigator may have increased Murtagh's group one haul for the season to 14.

Today's declaration stage for the King George will reveal much about tactics. O'Brien still has the option of running a pacemaker for his odds-on favourite - probably Red Rock Canyon - but he may decide that such a ploy would be more to the benefit of the second favourite, Youmzain.

Yesterday, while admitting that Youmzain must be held up whatever the pace of the race, his trainer Mick Channon claimed to be unconcerned. “Now that we know how to ride him, it doesn't matter how fast or slow they go,” he said.