Cheveley Park Stud rate Integral as their best chance of a winner at Royal Ascot this week ahead of her appearance in the Duke of Cambridge Stakes.
Michael Stoute's Dalakhani filly won a Listed prize and a Group Three as a three-year-old last season and was only a length behind 1000 Guineas and Coronation Stakes heroine Sky Lantern in the Sun Chariot at Newmarket.
The two do battle again over a mile on Wednesday, with Andre Fabre's French raider Esoterique adding further spice to the mix, having narrowly denied Integral in last month's Dahlia Stakes at Newmarket.
Cheveley Park's managing director Chris Richardson said: "We think she's a pretty special filly and she would be our favoured runner of the week.
"It is obviously a very tough race and Sky Lantern looks formidable opposition, but we are getting a bit of weight (5lb) and we hope our filly is progressive.”
Richard Hannon's four-time Group One winner Sky Lantern undoubtedly sets the standard, but has not been seen in competitive action since trailing home last of all in the Hong Kong Mile at Sha Tin in December.
Hannon said: "Sky Lantern has a 5lb penalty, which makes it difficult, but was there any point in going for the Queen Anne when she's got lots of big races ahead like the Falmouth and the Rothschild, then going abroad at the end of the year.
"She's 95% there, hopefully she'll be 100% with the run, but I'm happy with her and she's in good form.
"I think she's better than last year, she's got a big engine."
Esoterique's Newmarket triumph came as no real surprise as she showed top-class form last season when narrowly beaten in the French Guineas.
Fabre said: "She has been in good shape since her race at Newmarket. I am delighted with her.
"The ground will suit her, she is a consistent filly and I'm sure she will run a good race."
Esoterique is one of two runners fielded by Godolphin, with the Charlie Appleby-trained Certify another fascinating contender.
The American-bred filly was unbeaten as a juvenile, but missed her entire three-year old season through suspension following the Mahmood Al Zarooni scandal.
She made a winning return in the Cape Verdi at Meydan earlier this year before finishing fourth in the Balanchine and returns to British action for the first time since winning the 2012 Fillies' Mile.
Purr Along has always been a quality filly and made a winning debut for Johnny Murtagh in the Lanwades Stud Stakes at the Curragh last month.
David Redvers, racing manager for part-owners Qatar Racing, said: "She won nicely at the Curragh. She's come on leaps and bounds from that, Johnny couldn't be happier.
"I just can't wait to see her run against Sky Lantern and see if she can put it up to her.
"She had some minor back issues which have been treated and alleviated. She seems to have come forward for that."
Purr Along is reopposed by fellow Irish challenger Fiesolana, who was beaten just half a length in the Curragh Group Three.
Trainer Willie McCreery told At The Races: "She'll be there or thereabouts. If they go good and fast early on it will suit her. The better ground will suit her as well.
"This year it's been hard to get her fit. She's minding herself a little bit.
"She's stronger and is holding her condition well. You don't mind that - it's a long year for her. Her main aims are at the end of the year, but she'll turn in fitter this week."