Frankie Dettori has won the Prix de l’Arc de Triomphe six times, more than any other jockey. His mount this year, Torquator Tasso, has won the Arc once, one more time than any of the 19 horses he faces Sunday. His trainer, Marcel Weiss, insists Torquator Tasso is at least as good now as he was a year ago, when he shocked the racing world with a 71-1 Arc upset. The upset came on a rain-soaked, heavy autumn course at Longchamp – and have you looked at the Paris forecast? Rain was to start just before midnight Friday and fall, at least intermittently, all the way through the Arc card.