Rumplestiltskin did it the hard way in the Moyglare Stud Stakes at the Curragh as she charted a wide course when coming from last to first to claim the Group One prize.
Kieren Fallon was content to sit out the back on the 2/7f favourite in the early stages but had to go around the field when delivering his challenge inside the final two furlongs.
The daughter of Danehill showed a smart turn of foot to lead at the furlong pole and battled gamely to see off the persistent Ugo Fire by a neck. 100/1 shot Arbrae Lady ran a cracker to stay on for third.
'She pulls up when she gets there and is only as good as the horses she is racing against,' said winning trainer Aidan O'Brien.
'We'll see how she is but she is not definite to run again this season. She's a smart filly and the Guineas is definitely a possibility.'
Ladbrokes were unimpressed with the performance and pushed the winner out to 16/1, from 10/1, for next year's 1,000 Guineas.
Last year's Moyglare winner, Chelsea Rose, had earlier collected her third Listed contest of the season when taking the Dance Design Stakes in impressive fashion.
Con Collins' filly swooped into the lead a furlong-and-a-half from home and soon powered clear. Pat Shanahan could afford to ease down close home to beat Pictavia by two lengths.
'She's getting better all the time and we are very pleased with that - she did it easily,' said assistant trainer Tracey Collins.
'She will come back here for the Blandford Stakes (Sep 18th) and will then probably go for a fillies Group One in Rome on October 23rd (Premio Lydia Tesio). She will probably be kept in training for next year.'
Collins had earlier initiated a double when Persian Knight emerged on top from a close finish in the opening Free To Speak Apprentice Handicap.
Aussie Rules' inability to keep straight cost him victory in the Group 3 Go And Go Round Tower Stakes, as Abigail Pett finished well to pip him on the line.
The 4/6f looked set for victory after getting the better of an early duel with English raider Clare Hills, but drifted right across the track in the final furlong and was just caught by Jim Bolger's filly.
The winner had been in the Moyglare Stakes but was taken out at the forfeit stage due to a minor injury: 'Hopefully we will step her up now and we'll have a look at the Cheveley Park Stakes,' said Bolger.
English raiders dominated the field for the Nolan & Brophy Auctioneers Flying Five and duly supplied the first four home in the Group 3 event.
Benbaun, successful over course and distance in June, struck again for Mark Wallace. Jamie Spencer sent him to the lead two furlongs from home and the Stravinsky gelding stayed on well to beat The Tatling by a length.
Connections of Moyglare second Ugo Fire gained quick compensation when Kestrel Cross carried the same colours to success in the Ladbrokes.ie EBF Irish Cambridgeshire.
The gelding was completing a double for jockey Declan McDonogh, who had earlier teamed up with his father Dessie to take the Mooney's Of Monasterevin Handicap with Diamonds For Luck.
