It is 11 years since the Ballydoyle handler first claimed Europe’s premier middle-distance prize with Dylan Thomas.
O’Brien doubled his tally with Found in 2016 and launches another strong assault, numerically at least, on the ParisLongchamp showpiece on Sunday.
Kew Gardens is the yard’s chief hope under Ryan Moore after providing his trainer with a sixth victory in the St Leger at Doncaster three weeks ago.
O’Brien said on Saturday: “Everything has gone well since the Leger and we’ve been happy with him since.
“He has won around Longchamp – he won the Grand Prix de Paris there. He seems to be in good form.
“We were training him for the King George in the middle of the summer and he just had a setback with the rest of the horses (stable bug), so that’s why he didn’t get to go there.”
The apparent second string is Donnacha O’Brien’s mount Capri, who won last year’s St Leger before beating just one home in the Arc at Chantilly.
The grey son of Galileo made a successful start to the current campaign in the Alleged Stakes at Naas in April, but has run just once since, finishing fifth of six in the Prix Foy over this course and distance last month.
O’Brien added: “We thought that he would improve nicely from the last day and we’ve been happy with him since.”
Magical (Wayne Lordan), Hunting Horn (Seamie Heffernan) and big outsider Nelson (Michael Hussey) complete the quintet.