Cubanita ran out a game winner of the Dubai Duty Free Finest Surprise Stakes at Newbury.
Jim Crowley was in the saddle aboard the 7/1 chance who showed tremendous resolution to get the better of 11/4 favourite Noble Mission after a protracted duel.
It was only in the final 50 yards that the daughter of Selkirk finally took a decisive advantage and she went on to score by a neck in the Group Three contest.
Rawaki (33/1) ran a huge race in third, a further length-and-a-quarter adrift.
Disappointment of the race was the lightly-raced Mutashaded who folded tamely when the pace incresed two furlongs out.
"She worked well last week so we decided to put her in on Monday," winning trainer Ralph Beckett said.
"I was worried about running with a penalty but she has improved. "Miss Rausing is keen to try the Tattersalls Gold Cup in Ireland if the ground is soft, otherwise there's the Yorkshire Cup. "It all depends on the ground."