The Currabeg handler has won the Derby twice with Sinndar (2000) and Sea The Stars (2009) and this year saddles Ebanoran.
The Aga Khan's colt was first past the post in the Derrinstown Derby Trial at Leopardstown but subsequently demoted into second place.
Oxx is cautiously optimistic about his chances of adding to his Classic haul at Epsom, but accepts that the Aidan O'Brien-trained Australia, third in the Newmarket Guineas, is the one to beat.
He told the Irish Times: "The Guineas is traditionally always the best trial and the favourite looks tailor-made for the job at Epsom. Apart from the Guineas, it's hard to know which was the best trial, or if they were any good at all.
"But the two trials for a Derby horse in Ireland are the Ballysax and the Derrinstown and I think the Derrinstown was a good race this year. It's true the owner isn't into running no-hopers, and neither am I. We think this is a colt worth sending to Epsom. He's very well bred.
"We can't be sure about him staying the mile and a half but that isn't the worst complaint. You would rather that than going there with an out-and-out stayer. Epsom is a test of stamina and speed."
Assessing conditions at the Surrey track on Tuesday afternoon, clerk of the course Andrew Cooper tweeted: "First walk of @EpsomRacecourse for a few days - 36mm rain since Thurs and would call good to soft, soft places."
Leading challenger Geoffrey Chaucer has been taken out of Sunday's Prix du Jockey Club at Chantilly.
Also trained by O'Brien, the colt attracted plenty of Epsom support last week and he has now been ruled out of the French Classic, but Dante hero The Grey Gatsby still remains for Kevin Ryan while Roger Varian has Ayrad in the mix.
Prince Gibraltar, a Group One-winning juvenile and Prix Greffulhe hero, heads the field for Jean-Claude Rouget, who won the Classic with Le Havre back in 2009. The trainer also has Gonna Run under consideration.
French 2000 Guineas Karakontie remains on course for trainer Jonathan Pease, with Longchamp runner-up Prestige Vendome a possible to reoppose along with fifth-placed Galiway. Stillman and Wild Chief could add a German flavour to the 10-furlong showpiece.
Trainer Willie McCreery is confident Fiesolana can make her presence felt in the Duke of Cambridge Stakes at Royal Ascot following her narrow reverse at the Curragh. The daughter of Aussie Rules won five times during a fine 2013 campaign, and was snapped up to run in the colours of Flaxman Stables.
She was unable to make a significant impact upon her return at Saint-Cloud, but shaped much better when touched off by Purr Along in the Group Three Lanwades Stud Stakes on Saturday.
McCreery said: "She's good after the race and I was very happy. She ran very well and seemed to enjoy herself. The most important thing is that there's something to work with and she should come on a lot for the run.
"The race didn't suit her in France, but she didn't run too badly at all and we knew she'd improve for it. It's onwards and upwards to Royal Ascot. The Duke of Cambridge looks perfect with no penalty."
Royal Ascot could be next on the agenda for Maarek following his eclipse at the Curragh last Saturday.
The seven-year-old won the Duke of York Stakes at York earlier this month and trainer Evanna McCutcheon opted to make a swift return to tackle the Greenlands Stakes just 10 days later, where he eventually finished second to Slade Power.
McCutcheon felt he lost little in defeat and while he is entered in Sunday's Prix du Gros-Chene at Chantilly, Maarek is now likely to be lined up for either the King's Stand or Diamond Jubilee Stakes.