Group One winner Iridessa stars among 60 entries for the 2019 G1 Investec Oaks, the Epsom Downs Classic, details of which are revealed today.

The 12-furlong fillies' Classic is the highlight on day one of the Investec Derby Festival, Investec Ladies' Day, Friday, May 31, and carries a total prize fund of at least £500,000.

One of two Investec Oaks entries for Joseph O'Brien and owner Chantal Regalado-Gonzalez, Iridessa provided O'Brien with his first G1 success in Britain as a trainer when powering to victory in the Fillies' Mile at Newmarket in October.

The three-year-old daughter of 2013 Investec Derby winner Ruler Of The World, who is the 16/1 co-favourite of five with Unibet, official betting partner of the Investec Derby Festival, finished third on her 2019 return in the G3 1,000 Guineas Trial at Leoapardstown on April 6.

Chantal Regalado-Gonzalez is no stranger to success in the Investec Oaks, having seen her colours carried to victory by 50/1 outsider Qualify in 2015. The owner's other entry, Altair, by 2014 Investec Derby victor Australia, came late and fast to make a winning debut in a seven-furlong Dundalk Polytrack maiden in January.

Joseph O'Brien, who has been a trainer since June, 2016, missed out on partnering an Investec Oaks winner, but was twice successful as a rider in the Investec Derby on Camelot (2012) and Australia.

Joseph's father Aidan O'Brien, Ireland's champion Flat trainer for the past 20 years, who trained Camelot, Ruler Of The World and Australia, accounts for 19 Investec Oaks entries this year, the most of any handler, as he goes after a remarkable eighth Investec Oaks victory.

Aidan O'Brien's contenders include Hermosa (16/1 with Unibet), who chased home Iridessa in the G1 Fillies' Mile, and impressive G2 Rockfel Stakes scorer Just Wonderful (16/1). Promising maiden winners Chablis (16/1) and Pink Dogwood (25/1) are also engaged.

Dual Investec Oaks-winning handler Ralph Beckett has three talented entries for owner Waverley Racing, all sired by Lope De Vega. The unbeaten Manuela De Vega (16/1) defeated the boys in the Listed Silver Tankard Stakes at Pontefract in October, while Antonia De Vega (33/1) captured the G3 Prestige Stakes at Goodwood. Impressive Doncaster maiden scorer Dancing Vega (20/1) completes the trio.

The pick of the three French-trained entries is Camelot filly Wonderment (25/1),who has not been seen out since defeating Sydney Opera House by a neck in the 10-furlong G1 Criterium de Saint-Cloud in October, when she was the only filly in the nine-strong field.

Trainer Nicolas Clement revealed: "Wonderment has grown over the winter and looks a picture at the moment. I could not be happier with her.

"She was a Group One winner as a two-year-old, we have no doubts about her staying a mile and a half, and we think she will handle Epsom, which is why we decided to make the entry.

"She will start off in the Prix Penelope at Saint-Cloud on May 1 and then depending on how she gets on there, we have the option of the Investec Oaks or the Prix de Diane."

Andre Fabre is the most recent French trainer to have landed the Investec Oaks, courtesy of Intrepidity in 1993, and the handler has two entries this year in Villa d'Amore (20/1) and Tamniah (20/1), who are both twice-raced maiden winners.

Other notable Investec oaks entries include G1 Prix Marcel Boussac third Star Terms (Richard Hannon, 33/1), who hails from the family of outstanding 1982 Oaks heroine Time Charter, and highly-regarded Yarmouth scorer Frankellina (33/1), the pick of three entries for Newmarket-based trainer William Haggas.

Investec Oaks betting from Unibet, official betting partner of the Investec Derby Festival:

16/1 Iridessa, Just Wonderful, Hermosa, Manuela De Vega, Chablis; 20/1 Dancing Vega, Peach Tree, Secret Thoughts, Tamniah, Tarnawa, Villa D'Amore; 25/1 Goddess, Sparkle Roll, Fleeting, Pink Dogwood, Entitle, Nausha, Wonderment, Coral Beach, Happen, Queen Power; 33/1 Antonia De Vega, Star Terms, Zagitova, Frankellina, Anapurna, Lastochka, Blue Gardenia, Delphinia, Dubai Blue, Fabulist, Grace And Danger, Mannaal, Sh Boom; 40/1 Tauteke, Credenza, Star Catcher; 50/1 Bar