Best In The World has a lot to live up to given her name but she won the Listed Staffordstown Stud Stakes at the Curragh on just her second start.
Runner-up on debut, she was nevertheless sent off the 4-6 favourite and when Ryan Moore brought her alongside Rayisa entering the final furlong the result looked inevitable.
However, possibly showing signs of greenness, she needed to be driven right out to the line as Dolce Strega stayed on strongly from the rear and ran her to half a length.
By Galileo and out of a Group One winner in Red Evie, Best In The World is a full-sister to her Aidan O'Brien-trained stablemate Found.
"She came on nicely from Gowran and will make a lovely middle-distance filly next year," said O'Brien.
"Ryan said she feels like her sister (Found). You would have to be happy with that, and Ryan was kind to her."
Earlier in the day, Black Sea comfortably opened his account at the second time of asking in the Irish Stallion Farms EBF Maiden, the first leg of a double for O'Brien and Moore.
An eyecatching fourth on his debut at Gowran three weeks ago, the Galileo colt always looked in command here with Moore putting the race to bed inside the final furlong on the 5-6 favourite who beat 100-1 shot Red Rannagh by two lengths.
O'Brien said of Black Sea: "He'd a nice run in Gowran. He was a bit free going to the start on that occasion and Seamie (Heffernan) dropped him in and he came home well.
"He settled well today and is a nice horse to have going into next year."
Fort Del Oro (3-1) looks like taking high rank in the sprinting division next season after winning the Waterford Testimonial Stakes For The Defence Forces Cup.
Eddie Lynam's filly had shown decent form already when third to Mattmu and second to Lucky Kristale at York, and took another step forward in this Listed race.
Billy Lee was always cruising on the three-year-old, who was unraced at two, but Moore emerged from the pack on The Happpy Prince and looked a real threat.
To Fort Del Oro's credit, she battled well to win by a length and a half at the finish. Gathering Power, a stablemate of the winner, was third.
"This has been a lucky race for me," said Lynam.
"She did it well and has an entry next week in the big sprint at Ascot. If she is jumping out of her skin we will probably let her take her chance.
"She's a good filly and I think she will improve from three to four. She'll get seven furlongs."
