Talking Horses: Six key questions ahead of this year's Arc 

Having had a light season, hopes are high that the step up to a mile and a half will see Luxembourg peak in Longchamp

Luxembourg was hugely impressive when winning the Irish Champions Stakes and a similar display in Sunday's Arc will give him every chance of victory in Europe's premier middle-distance contest. Picture: Seb Daly/Sportsfile

Should Luxembourg prevail, would it be Aidan O’Brien’s finest feat yet?

It would have to be up there given few were rushing to back Luxembourg to win the Qatar Prix de l’Arc de Triomphe when the Camelot colt scrambled home at odds of 2-9 in the Group 3 Royal Whip Stakes at the Curragh in August.