By Andy Stephens
Ryan Moore switched to Magical after the late withdrawal of Clemmie and that meant O'Brien Jr, who had been scheduled to partner that filly, switching to Happily. The pair dominated the finish, with the latter edging ahead late on.
It capped a testing time for Moore after his defeats aboard stable stars Winter and Churchill the previous day at Leopardstown.
Magical had beaten Happily into second and another Ballydoyle inmate September into fourth place when landing the Debutante Stakes over the course and distance three weeks ago and the 9-4 favourite looked likely to follow up after kicking clear in the hands of Ryan Moore.
However, 13-2 shot Happily found top gear late on and got up to score by a short head. September rounded off a one-two-three for the trainer, almost four lengths away from the front two.
"Happily toughed it out and Ryan's filly (Magical) ran a stormer as well. Donnacha gave her a great ride," O'Brien Sr said: "He was delighted to be on Happily. In all fairness, they never question anything and that was just the way it happened.
Happily and Magical do battle in the Moyglare
"When the other filly (Clemmie) didn't run, Ryan got on Magical. It's strange the way things happen. All the fillies that ran are seven-furlong or mile fillies. I wouldn't shorten up any of them.
Moore's mood would not have been improved earlier in the day when Gustav Klimt, odds-on favourite for the Goffs Vincent O'Brien National Stakes, was withdrawn after suffering a stone bruise.
In his absence, Verbal Dexterity stretched clear for an impressive success.
The Jim Bolger-trained colt, sent off at 5-2, made a huge impression when making a winning debut over the course and distance in early June before finding Beckford too strong in the Railway Stakes.
Having since been narrowly denied in the Phoenix Stakes, Beckford was the 6-4 favourite to go one better and provide Gordon Elliott with a first Group One victory on the Flat, but 5-2 chance Verbal Dexterity turned the tables on him instyle.
Verbal Dexterity and O'Brien's Rostropovich were both being ridden passing the two-furlong marker and Beckford looked likely to assert after looming up ominously under Pat Smullen.
But Verbal Dexterity responded generously to Kevin Manning's urgings to stay in the fight and he eventually came home with three and a half lengths in hand.