Discourse suffered a fracture in the 1000 Guineas at Newmarket and the Godolphin filly could miss the entire British Turf season.
The daughter of Street Cry, the Dubai World Cup winner, beat home only stablemate Lyric Of Light in the Classic 10 days ago.
Discourse was ridden by Mickael Barzalona and although the filly was hampered at the start of the race, she was soon beaten. The French jockey virtually pulled up his mount and the pair finished 44 lengths adrift of Moonstone Magic, who was 15th.
Lyric Of Light was seven lengths last under Frankie Dettori.
"It is a great shame as she will miss the summer highlights but hopefully she will be back on the racecourse before the end of the season," said Simon Crisford, Godolphin's racing manager.
Mahmoud Al Zarooni, the trainer, was nonplussed after the race and although he sought refuge in the excuse that the going was testing it was only good to soft.
It was the second high-profile injury this year to one of his leading ladies following the surgery required by Gamilati, the UAE 1000 Guineas victor.
Gamilati had a chip removed from her near-fore ankle in March which forced her to miss the English Classic. She also missed several weeks training as a result but is likely to race towards the end of the British season.
It is an important week for Al Zarooni, who runs Mandaean in the Dante Stakes at York on Thursday in an effort to decipher whether he is good enough to take on Camelot, the 2000 Guineas winner, in the Derby at Epsom next month.
He also has City Style running at Kranji Racecourse, in the US$3 million (Dh11m) Singapore International Cup on Sunday.
The six-year-old gelding was campaigned heavily at Meydan Racecourse during the Dubai World Cup Carnival, culminating in a third-place finish behind the impressive Cityscape in the Dubai Duty Free in March.
City Style was the final international challenger to arrive in Singapore, late on Monday night, after Al Zarooni and Sheikh Mohammed bin Rashid, Vice President of the UAE and Ruler of Dubai, decided to re-route the horse from travelling to England.
"We gave him a little rest after racing on World Cup night and kept him doing some light exercise. He was in good condition and Mahmoud and Sheikh Mohammed then made the decision to send him out here," Andrea Mascolo, Godolphin's travelling head lad, said. "He was in quarantine and we did think about giving him a good holiday, but he was so well in himself that we thought, 'Why not come here?'"
Krypton Factor and Rocket Man were set to clash in the Krisflyer International Sprint, also on Sunday, but Rocket Man has been taken out of the Group 1 contest by Patrick Shaw, the trainer.
Rocket Man, the 2011 Dubai Golden Shaheen winner, could not follow up in the UAE leg of the Global Sprint Challenge this season, when outrun by Krypton Factor at Meydan.
Rocket Man has suffered a ligament strain to his near foreleg and has been scratched as a precautionary measure.
"It's like twisting an ankle," Shaw told the Singapore Turf Club. "All it needs is rest and he will get over it.
"If we were to press on it could cause long-term damage or, even worse, irreparable damage, and that was not a risk I could take, and remember he has a screw in the other leg as well."
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