With the Arc trials at Longchamp on Sunday afternoon to weigh up in addition to four Group Ones on the second day of Ireland’s Champions Festival at the Curragh, many punters will have had a severe case of information overload as a weekend with top-level action in four countries and on two continents finally drew to a close.

Oisin Murphy and William Buick, who both contested Grade One events at Woodbine in Toronto, Canada on Saturday, before a transatlantic hop to ride in Ireland a few hours later, would probably share the general sense of exhaustion. The autumn is upon us, and with it the career-defining races that will crown the champions of 2024 in every generation and division.

The ante-post markets for next year’s 1,000 Guineas, 2,000 Guineas and, more immediately, the Prix de l’Arc de Triomphe at Longchamp on 6 October were all the subject of significant shake-ups on Sunday afternoon, and the imminence of Europe racing’s showpiece event means that it is the obvious place to start.

Look De Vega went into Sunday’s Group Two Prix Niel as the unbeaten winner of the Prix du Jockey Club (French Derby), and the clear market leader for the Arc with British bookies at around 7-2. He emerged without either his unblemished record or Arc favouritism having finished only third of the five runners behind André Fabre’s Sosie, who duly replaced him at the top of the betting at around 5-1.

It is a race that is likely to rack up plenty of views on YouTube over the next three weeks, as punters across Europe weigh up the relative merits of French, British and Irish middle-distance form. It also raises the distinct possibility of a record-extending ninth Arc victory for the greatest French trainer of all time and, some would argue, the finest that Europe has seen too.

Trial races like the Niel can wax and wane in terms of their significance, but it still feels a little surprising that the last colt to complete the Niel/Arc double in the same year was the Fabre-trained Rail Link in 2006. Throughout the 1990s and the first few years of the 2000s, Niel winners went on to land the Arc with remarkable regularity, including Carnegie (1994), Helissio (1996), Sagamix (1998), Montjeu (1999), Sinndar (2000) and Hurricane Run (2005).

Since Rail Link’s year, though, the race has entered a lean period in terms of its relevance to the Arc, which may reflect an increasing reluctance among leading trainers to bother with trial races at all given the much-expanded global programme, in the autumn in particular, and the desire to keep their horses fresh.

Fabre, though, is old school, and in a league of his own when it comes to preparing a lightly-raced, late-developing three-year-old colt for the Arc.

Sosie finished just over two lengths behind Look De Vega in the Prix du Jockey Club – which has been run over 10 furlongs, rather than the “classic” Derby trip of 12, since 2005 – but improved to win the Grand Prix de Paris, over the Arc course and distance, in July. And unless Fabre has suddenly forgotten everything he has learned about training horses for the Arc over the 40-or-so years since Trempolino – another Niel winner – gave him his first win in 1987, you can be sure that Sosie will improve for Sunday’s outing.

The same, of course, is surely true of Look De Vega, who did not see a racecourse until November last year and won the Jockey Club in early June on just his third outing. He remains second-favourite for the Arc at around 6-1, with the Japanese challenger, Shin Emperor, and Aidan O’Brien’s Los Angeles, the Irish Derby winner, who were separated by a head when third and fourth respectively in Saturday’s Irish Champion Stakes, next in at 8-1 and 10-1 respectively.

British-trained Arc contenders are a little thin on the ground, although Ralph Beckett’s admirable Bluestocking, who landed another of Sunday’s Arc trials, the Group One Prix Vermeille, certainly deserves her place in the field and can be backed at around 12-1.

O’Brien’s Lake Victoria was the main mover in next year’s Classic markets on Sunday after beating a field that included a better-fancied stable companion in Bedtime Story in the Group One Moyglare Stud Stakes.

She is now joint-favourite for next year’s 1,000 Guineas alongside another O’Brien-trained filly, Fairy Godmother, but the stable suffered a surprising reverse in the card’s second two-year-old Group One, as Henri Matisse, the 5-6 favourite, surrendered his unbeaten record behind Joseph O’Brien’s Scorthy Champ (12-1) in the National Stakes.

The pecking order among the juveniles will come steadily into focus over the coming weeks at Longchamp, Newmarket and Del Mar in California, but if there is one prospect that looms above all others after a frantically busy weekend on the track, it is surely the chance that at 78 years of age, André Fabre could become the first trainer to saddle an Arc winner in five different decades. Longchamp is the next stop on racing’s annual world tour, when Sosie will be the centre of attention.