Sinndar battled on to win by a head from Murawwi with Jammaal a length back in third. Johnny Murtagh, the winner's jockey, said, "He put his head down and really tried for me. I thought they might come back to us and I knew Sinndar stays well, so I was always hopeful."
The Aga Khan, Sinndar's owner, said: "I think Sinndar will be a smart horse over a mile and a half next year. He is out of a very good staying family and, as a son of Grand Lodge, he should have the pace to win some nice races for us, so I doubt if he will run again this season."
John Oxx, the winning trainer, said: "He is tough and very honest and is an outstanding individual for whom we always have had high hopes on looks."
O'Brien said of Bernstein: "He ran too freely early on, according to Michael Kinane, and then got tired in that ground." Bernstein was later found to have a "respiratory abnormality".
Earlier in the afternoon, Insatiable, trained by Sir Michael Stoute at Newmarket, won the Blandford Stakes. Insatiable, the 2-7 favourite, quickened easily for Kinane past Theatreworld inside the two-furlong marker and could now head to Newmarket for the Champion Stakes.
O'Brien's two-year-old Inkling could run in the Cheveley Park Stakes at Newmarket after winning the six-furlong maiden, while Tony Martin's She's Our Mare may go for the Cambridgeshire there after her success yesterday.