So, the Rock will be rolling for the last time in Chicago on Saturday. Rock Of Gibraltar, the colt who has captured the imagination like no other this year, leads the European charge across the Atlantic to the world's richest raceday, the $13m Breeders' Cup meeting at Arlington. He goes there on the most prolific success spree ever recorded at this level of the sport, with seven consecutive Group One races under his girth, yet the debate still rages as to whether he can step on to the pantheon as a giant of the Turf.
Sir Alex Ferguson, whose colours the Aidan O'Brien-trained three-year-old carries, is a man who should recognise a winner when he sees one. He does not mind, though, that his amazing horse has not yet been unanimously declared a champion.
"There's nothing wrong with opinions and controversy," he said. "People discussing whether George Best was the best, or Ryan Giggs or David Beckham. Debates like that keep all the interest going. And to be honest, for the Rock just to be named in the same sentence as horses like Mill Reef and Brigadier Gerard is fantastic."
Ferguson acquired a half-share in Rock Of Gibraltar from John Magnier and his Coolmore Stud associates in June last year, soon after the horse had been beaten at Royal Ascot. The record sequence started more than three months later and has taken the Manchester United manager on a fairytale journey beyond his imagination.
Anecdotally as dour as befits a son of Govan, he finds release and relaxation on the racecourse. "I caught the bug at Cheltenham four years ago," he said, "and when my first horse, Queensland Star, won his first race, a maiden, I thought that was the best day of my life.
"But with Rock Of Gibraltar, I am living a dream. I never thought the horse would get to this level. I don't think anyone did and the thing is to just relish his achievements and enjoy the merry-go-round."
Ferguson is under no illusions as to the severity of the Rock's task on Saturday. Team Europe, traditionally the Breeders' Cup underdogs, have netted just 21 victories in 18 editions of the meeting and Arlington, hosting the extra-vaganza for the first time, is a tight track. In the Mile there is less than a furlong to the first turn.
"To go there and take on the best of the Americans on an unfamiliar track, and with the travelling, is hard. But the horse is tough and has courage, which are great qualities in any athlete."
Rock Of Gibraltar has won 10 of his 12 races and is unbeaten in five, all over a mile, this term. His latest outing, a defeat of Banks Hill in the Prix du Moulin at Longchamp last month, took him past Mill Reef's mark of six Group Ones in a row and equalled the five in a single campaign of another petrologically-named Ballydoyle inmate, Giant's Causeway.
But perhaps it should be remembered that Brigadier Gerard put together a string of 10 consecutive unbeaten runs in races that are now Group Ones, even if they were interspersed with Group Two contests.
To imply that Rock Of Gibraltar is in any way better than Mill Reef is an insult to a superlative champion. And as a miler, O'Brien's charge would not have seen which way the Brigadier, El Gran Senor, Dancing Brave or even Mark Of Esteem went. He is not yet great, but he is very good indeed and his progress and professional, consistent, reliable and generous attitude to his job have been a delight to witness. Keen he may be, Keane he is not.
And there is no doubting the bonny bay's charisma. When he turned up at Ascot recently for an exercise gallop after racing, hundreds remained to watch and to cheer him up the straight and wish him bon voyage ahead of his American venture. His fanbase has extended to Manchester United supporters worldwide and closer to home.
"The Old Trafford players have taken an interest," confirmed Ferguson, whose day job (a match with Aston Villa) means he must watch the Rock's date with destiny from his home in Cheshire. "Although it's usually to ask me for tips and whether they should back him. They won't have got much of a price lately but then with the amounts they can afford to put on they wouldn't need to."
Rock Of Gibraltar is favourite for the $1m Mile, one of the three turf races on the eight-contest card, at around 5-4, the first time he has been odds-against since beating stablemate Hawk Wing in the 2,000 Guineas.
The O'Brien squad forms the largest single unit in the 17-strong European challenge, with Landseer also in the Mile, Hawk Wing bidding to redeem his reputation in the $4m dirt finale, the Classic; dual Derby winner High Chaparral in the $2m Turf; Reach For The Moon in the $1m Juvenile Fillies and Hold That Tiger heading a possible three-strong attack on the $1m Juvenile, so memorably won by Johannesburg for Ballydoyle last year.
The British raiding party is five-strong. The Sir Michael Stoute-trained Golan tackles the Turf, in which Ballingarry, transferred from Ballydoyle after his recent Canadian International win, may provide a stern local defence, and Luca Cumani's charge, Gossamer, has the Mile as her first preference.
Three high-class females line up against US star Golden Apples for the Filly And Mare Turf: Golan's stablemate Islington, Zenda (John Gosden) and Godolphin's dual Classic heroine, Kazzia. The blues also field Imperial Gesture (Distaff) and E Dubai (Classic) from their American base.