Winner of the John Smith’s Cup at York over 10 furlongs back in June, Sinjaari did try 12 furlongs twice as a three-year-old.
With another year on his back, Haggas is hoping to open up a few more options with next season in mind if his stamina lasts out.
Most recently Sinjaari finished second to Dubai Warrior in a fast-track qualifier for Finals Day at Lingfield.
“We are trying him over a mile and a half again, as knowing whether or not he gets the trip will help with plans for next year,” said Haggas.
“When he runs over 10 furlongs, he shapes as if he will get a bit further, and Tom (Marquand) feels he will as well, so we will see. I think he will be OK.”
Sinjaari is joint-top-rated along with Sextant, who is now with Keith Dalgleish having left Sir Michael Stoute.
Andrew Balding’s Johnny Drama arrives having won his last three, while Ed Dunlop’s Red Verdon will be ridden by Ryan Moore for the first time this year.
Joseph O’Brien sends two over from Ireland in the shape of Snapraeceps and Sagrada Familia.
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