The four-year-old has been on the easy list since he defeated the reopposing Algometer by a length and a quarter to take the Group Three spoils in the Brigadier Gerard Stakes at Sandown in May.
However, the son of Dubawi is reported back in fine form and has been pleasing his trainer Sir Michael Stoute ahead of his appearance in the Group Two feature on the Knavesmire.
Chris Richardson, managing director for owner-breeders Cheveley Park Stud, said: "Hopefully the ground will be OK for him.
"He had a bit of a dirty scope post-race (following Sandown) and in the intermediary period, so he just needed some treatment.
"He's fine now and back on track and we're looking forward to him taking his chance.
"He's one of the leading contenders in the race."
Ken Condon is looking forward to bringing Success Days back to the UK and will be hoping for better luck than on his only previous visit, when he was well beaten in Golden Horn's Derby two years ago.
The five-year-old grey has been a regular in top-quality races over this trip in his native Ireland and takes his chance on the back of being collared close home by Johannes Vermeer in the Group Three International Stakes at the Curragh earlier this month.
"The track at York should suit him well and he ran a good race at the Curragh last time," said the County Kildare handler.
"Johannes Vermeer was a Group One winner as a two-year-old and looked on the way back after a good run at Ascot.
"He was in receipt of 3lb, although there is no question he won cosily at the line.
"The ground was a bit quicker than ideal for Success Days, so all things considered I was very pleased."
Andrew Balding saddles Elbereth, who finished fourth in the Coronation Cup at Epsom but was down the field in the Wolferton Handicap at Royal Ascot.
The Kingsclere handler said: "She's in great form and did well over course and distance in the John Smith's Cup last year (runner-up).
"On the best of her form this year she should be very competitive.
"She had bad draw and got a bad trip on her last run at Ascot.
"She was beaten a long way and came there with every chance but she had done too much early on from the wide draw.
"The going shouldn't be a problem as the going should be good by the time of the race."