Zawraq will miss the Investec Derby at Epsom on Saturday.
Dermot Weld's colt has not fully recovered from a minor setback he suffered earlier in the week and will play no part in the premier Classic.
Angus Gold, racing manager for owner Sheikh Hamdan Al Maktoum, said: "It's bad news.
"He did a bit of work this morning and moved beautifully under Pat Smullen, but by the time he got back to the yard he was definitely not right again.
"It's very bad timing."
Zawraq had been prominent in the ante-post betting lists for the Derby after convincingly winning his two starts to date.
But after completing a satisfactory piece of work on Tuesday morning, he was found to have been slightly lame upon his return to the yard.
Initial X-rays and scans suggested the injury was not serious, with hopes high in the Weld camp he would prove his fitness in time for Epsom.
Zawraq engaged in promising light exercise on Wednesday, further fuelling the optimism, but connections were forced to draw stumps after the horse cantered on Thursday morning.
Gold said: "He (Smullen) said that when Zawraq flexed one of his joints he was a bit sore.
"Maybe it is something do with a joint that did not show up on the scans or X-rays.
"Hopefully it's nothing too serious, but we can't think about future plans until we get to the bottom of what is troubling him."
Ireland still has a strong hand after Aidan O'Brien declared Giovanni Canaletto (Ryan Moore), Hans Holbein (Seamie Heffernan) and Kilimanjaro (Joseph O'Brien).
Success Days and rank outsider Carbon Dating also make the journey across the Irish Sea.
Ante-post favourite Golden Horn has stood his ground, as, too, has stablemate Jack Hobbs.
There is, however, a slight question mark over the suitability of the ground for the latter.
Trainer John Gosden said: "I'll walk the track on Saturday morning.
"The ground is perfect right now, but we'll see what the weather does and whether they get a thunderstorm.
"I'm happy with all the horses."
Elm Park is given the chance to shine by Andrew Balding and owners Qatar Racing.
The Group One-winning colt, third behind Golden Horn and Jack Hobbs in the Dante at York, is joined in the line-up by German challenger Rogue Runner, who is also owned by Qatar Racing.
Epicuris, Moheet and Storm The Stars complete the final field.
Godolphin's Best Of Times and the Balding-trained Rocky Rider were also withdrawn.
Heading the home team is Michael Stoute's Crystal Zvezda, a hugely impressive winner of a Listed event at Newbury last month.
Richard Hughes will be on board as Stoute bids for a third Oaks - and a first since Unite in 1987.
"She took a long time to come to herself this spring and then suddenly a week before her Newbury race she showed a real spark so we were confident she would run a big race," said Stoute.
"We have always liked her a lot - she is very talented."
John Gosden won his first Oaks with Taghrooda 12 months ago and this year saddles two major contenders in Pretty Polly winner Jazzi Top and Musidora scorer Star Of Seville.
The latter bids to give owner-breeder Lady Bamford a second Oaks victory following Sariska's triumph in 2009.
The owner's racing manager Hugo Lascelles said: "We were very pleased first time out this year at Newbury and then she went to York.
"It was a small field, she had to do it all herself and was having a look around at the end.
"Sariska was a brilliant filly and won the Musidora with some authority, whereas Star Of Seville won narrowly and was getting weight from the runner-up.
"I thought it was a very satisfactory performance but whether it is good enough to win an Oaks, only time will tell."
Frankie Dettori had the choice of the Gosden pair and went for Jazzi Top, whose sister, Izzi Top, was third in the 2011 Oaks.
Mark Weinfeld, for owners Meon Valley Stud, said: "To have another contender for the Investec Oaks is a great position to be in.
"I think Jazzi Top and Izzi Top are fairly similar types, excepting that Izzi Top liked some cut in the ground, whereas Jazzi seems happy on all surfaces.
"I am very excited ahead of Friday but not at all confident!
"We don't really know how good Jazzi Top is, but she won an Oaks trial so is entitled to take her chance.
"Even the best filly on the day needs luck in running in what can be a tough-and-rough race."
Ralph Beckett knows what it takes to win the Oaks, having landed the prize with Look Here (2008) and Talent (2013), and this year saddles outsider Bellajeu, runner-up in the Lingfield Oaks Trial.
Beckett said: "Bellajeu has been training well since Lingfield and I am happy with her condition and how she is looking.
"I wouldn't say we are tilting at windmills but she is still a maiden and we are coming off only a placed effort in the Lingfield Trial.
"Having said that, I think she is still coming forward and it's worth a shot."
An Oaks triumph has so far eluded dual Derby-winning trainer Luca Cumani, but the Newmarket-based Italian has genuine hopes of getting off the mark with impressive Goodwood scorer Lady Of Dubai.
"She couldn't have done it any easier and on a tricky course like Goodwood bodes well for her ability to handle Epsom," Cumani told At The Races.
"She's a beautifully bred filly, a very well-balanced filly, and she's entitled to take her place in a year in which the Classic is quite open."
An 11-strong field is completed by Andre Fabre's French contender Al Naamah.
The daughter of Galileo enjoyed a spin on the Downs at last week's Breakfast With The Stars morning, just as the trainer's Pour Moi did before his victory in the Derby four years ago.
"The experience of bringing over Pour Moi before his Derby victory was so good that we decided to repeat it," said Fabre.
"Coming to Epsom beforehand is a great addition to the training.
"This course is very peculiar and horses need to see the bend and the downhill - so different to regular courses.
"It makes a big difference for the jockey, as well.
"Al Naamah is a fantastic-looking filly with a great pedigree.
"She is a potential Group One filly, but is still big and backward, but I think she is ready for the Oaks."
