Aidan O'Brien got off the mark for Royal Ascot 2012 as apparent second-string Ishvana claimed the Jersey Stakes.
The master of Ballydoyle also saddled leading fancy Reply, ridden by his son Joseph, but he failed to make an impact in the Group Three contest.
Although Ishvana had filled the runner-up spot in the Irish 1,000 Guineas on her latest appearance, she was allowed to go off at 20-1.
Seamie Heffernan sent his mount to the lead passing the two-furlong marker and she galloped all the way to the line to score decisively by a length.
Sentaril finished off strongly to pip favourite Aljamaaheer for the runner-up spot.
Anne-Marie O'Brien, who owns and bred the filly, said: "It's absolutely incredible. I'd like to thank my dad who bought her at the sales for us, he's picked out all our broodmares. We're so happy to be here.
"She was very impressive and showed a great turn of foot.
"There are lots of races to run all our fillies in and they all want slightly different trips, I think seven furlongs suited her perfectly today."
Aidan O'Brien said: "She had a very good run at the Curragh last time. She's a smart filly, she loves fast ground and shows plenty of speed.
"She got a great ride and it's been a top effort from everyone.
"You see a pecking order as it goes along on the track, we don't work them together at home."
Heffernan said: "It was extremely straightforward. She had a good run in the Guineas and she handles fast ground.
"It takes her a while to loosen up but once I took her to the outside, she went. She's a Group winner now.
"That's my first Royal Ascot winner. I'm experienced now so I take everything in my stride but it's nice to have it on the CV."
William Haggas said of Sentaril: "She ran very well, Johnny (Murtagh) thought they didn't go fast enough early so they didn't fan out as much as he'd have liked.
"She didn't get the clearest run from the two pole but it was still a good run.
"I'm not sure what's next, she's had a hard race, but I suspect she'll stay in training next year if the owners allow me."
Roger Varian said of Aljamaaheer: "He ran a great race. I suppose we weren't quite where we would have liked to have been in the field. The winner kept on well and it bodes well for the future.
"He's in the July Cup but probably won't run in that."
Heffernan, however, was suspended for seven days (July 4-10) and fined £550 for using his whip above the permitted level.
Murtagh was found guilty of the same offence to a lesser extent and was given a two-day ban on the runner-up.