The Juddmonte Irish Oaks has attracted a field of 11 for Saturday's Group 1 Classic at the Curragh, bringing together Epsom Oaks winner Thundering On, leading Royal Ascot performers Earth Shot and Johanna Walsh, the unbeaten Sparan Nua and a five-strong challenge from Aidan O'Brien.

Thundering On arrives with the strongest Classic credentials after her impressive victory at Epsom last month. She now attempts to complete the Oaks double and heads a three-runner team for Joseph O'Brien, who also saddles Johanna Walsh and supplementary entry Rebel Moon.

The Ribblesdale Stakes at Royal Ascot provides another significant form line. Earth Shot and Johanna Walsh, who finished first and second respectively, renew rivalry at the Curragh as they step into the Irish Classic.

Earth Shot represents William Haggas and is one of two British-trained runners in the field. David Menuisier sends out Inis Mor, who was one of three fillies supplemented for the race earlier this week at a cost of €50,000.

The other supplementary entries are Rebel Moon and the unbeaten Sparan Nua, whose rapid progression has earned her an opportunity at Group 1 level. Jim Bolger's filly made it three wins from three when landing last month's Group 3 Munster Oaks, having previously won at Naas and Gowran Park.

Bolger, who won the Irish Oaks with Give Thanks in 1983 and Margarula in 2002, believes Sparan Nua approaches her first Classic assignment from a different background to his previous winners.

"Both of those Oaks fillies were hardened campaigners, and they were well up for it on the day," Bolger said. "Sparan Nua hasn't had a proper Classic preparation mainly because she was a little bit weak last year, so we left her alone and we didn’t start back with her until well into the new year. I must admit she has surprised us somewhat, but we are all ready for Saturday."

Sparan Nua raced in the Bolger silks when winning her first two starts before carrying the colours of new owners Newtown Anner Stud to victory in the Munster Oaks.

Aidan O'Brien is responsible for almost half the field as he pursues a record-extending ninth Irish Oaks victory. Amelia Earhart, Beautify, Cameo, Composing and Sugar Island make up his five-runner challenge.

The composition of the field gives the race several distinct strands of form. Thundering On brings Epsom Classic form, Earth Shot and Johanna Walsh arrive through the Ribblesdale, while Sparan Nua puts her unbeaten record on the line after progressing through the Munster Oaks. The three supplementary entries add further depth to a race featuring leading representation from Ireland and Britain.

Irish Oaks Runners and Riders

Amelia Earhart – Ryan Moore
Beautify – Ronan Whelan
Cameo – Chris Hayes
Composing – Gavin Ryan
Earth Shot – James Doyle
Inis Mor – Oisin Murphy
Johanna Walsh – Colin Keane
Rebel Moon – Joey Sheridan
Sparan Nua – Declan McDonogh
Sugar Island – Wayne Lordan
Thundering On – Dylan Browne McMonagle

With the Epsom Oaks winner at the centre of the field, the leading Ribblesdale form represented and several less exposed fillies facing their first major Classic examination, the Irish Oaks brings together established form and emerging potential over the Curragh's Classic distance.

Image GBI racing