"Aidan told me the horse was having his midday nap," the great punting owner told The Independent. "We could go and have a cup of tea, but we had to leave him alone for an hour and a half. But the horse wasn't to be disturbed."
Even for a racehorse, Istabraq is a funny creature. He wakes up at a exactly the same time each morning and does exactly the same amount of routine work along exactly the same route. He jumps only one hurdle at home all year. He is virtually institutionalised.
It has to be this way with the seven-year-old because, like many brilliant athletes, he is on the verge of being bonkers. "He can go in an instant," O'Brien says.
When you take Istabraq away from the comfort of accustomed surroundings he starts to panic. At the Cheltenham Festival 12 months ago he sweated profusely before his race. The previous year he was even worse and you could have filled a cistern with the creamy perspiration that dripped from his body. The bad news for those who will attempt to wrest the Champion Hurdle crown from Istabraq at 3.15 this afternoon is that on both those occasions the horse won. His running more than made up for any mental fragility.
And Istabraq has changed this year. His mind seems clearer, his body is different too. We associate the champion with the sleek lines of the Flat horse he was bred to be, but now there is substance to him. "He's a small-looking horse but he's very deceiving," O'Brien says. "He's almost 16.1 [hands high]. He has a different look about him now. He's just getting stronger and stronger.
"He's very straightforward and a clean-winded horse and as he gets older he takes his work easier and that gives him a good chance. His races have been a lot easier this year than last."
It is a wonder to understand from where O'Brien gets this last belief - Istabraq has not had a race this season. He has had four canters which just happen to have been conducted in the forum of a race at the track. The trainer himself admits his horse's latest Leopardstown victory was incorporated into the schedule as a piece of fine-tuning. This is a cataclysmic thought for the 13 who dare take him on this afternoon. (Of the 17 which opposed last season only his stablemate Theatreworld and Bellator, a 66- 1 chance, have the nerve to try again).
Foremost among the challengers is French Holly, who was runner-up to Istabraq at Leopardstown in January. That result was a rare creature: a one-length annihilation.
French Holly had previously proved he was Britain's best protagonist in the Christmas Hurdle at Kempton. Like Istabraq he is both sired by a Classic Flat horse (the pair are by Sadler's Wells and Sir Ivor respectively) and a former winner of the Royal & SunAlliance Hurdle, a contest he won by 14 lengths last year.
Indeed, if Istabraq was not around, connections of French Holly could quite sensibly see several seasons at the top over timber for their horse. As it is though, the behemoth who looks as though he should be kept in a hangar rather than a box may be forced to go over fences if he is humiliated again today.
Theatreworld must also be a place consideration as he has been runner- up for the last two years. He usually plods along all season with a preparation culminating in success at Gowran Park. This time he did not win in Co Kilkenny, but then he did not have his ears pushed off either.
After that in the betting lists we are down to the likes of Lady Cricket, who would need to set off at daybreak to be given a chance. It was a struggle for her to win a three-runner, sports-day race at Fontwell last time. The rest have little chance on any known earth form.
It appears the Champion Hurdle is about to be returned to its glory years, when it was an uplifting contest dominated by multiple winners. Night Nurse, Monksfield and Sea Pigeon were dual victors of the Seventies and early Eighties, but in recent years the perennial winner is no longer a feature. See You Then was the last horse to follow up in completing his hat-trick in 1987.
Istabraq is now a bigger horse, both in physique and achievement, as we embark on the Cheltenham Festival of 1999. He seeks to emulate Monksfield, who was the last dual Irish winner, in 1978 and 1979, and there is no cogent argument which suggests he is not up to the assignment.
Racing people are not able to say this very many times at the Festival, but this year, in the last Champion Hurdle of the millennium, we can say it about Istabraq (3.15). He cannot be beaten.
Nap: Step On Eyre
NB: Ebullient Equiname