Trainer Joseph O'Brien says Thundering On is not yet certain to run in the Prix de l'Arc de TriompheSportSep 24 at 9:48 AM – Sep 24 at 1:41 PM4 outletsIrish ExaminerThundering On not certain for Arc seen Sep 24 at 1:30 PMRacing PostDylan Browne McMonagle in race against time to partner leading Arc hope Thundering On as Joseph O'Brien says: 'There's a chance' seen Sep 24 at 12:43 PMOxford MailThundering On yet to be committed to Arc challenge seen Sep 24 at 10:02 AMThe ArgusThundering On yet to be committed to Arc challenge seen Sep 24 at 9:48 AM