On Friday, the 24-year-old from Sydney made the first hole-in-one of the championship on the eighth at Royal Porthcawl, in Wales. Then on Sunday, she unwittingly assisted with the second.
England's Mimi Rhodes made a hole-in-one on the par-three fifth, but only because her tee shot glanced off playing partner Kyriacou's ball, which had left a couple of inches from the hole. Snooker-style, Rhodes' ball ended up in the cup.
Her shot would certainly have rolled past had it not been for Kyriacou's golf ball being in the way. Kyriacou went first and nearly made her second ace until her ball rolled just left of the hole.
Asked if she was the luckiest person in golf, Kyriacou replied: "I am. We actually just watched the video, and it hit my ball, and it went in. So I'm kind of claiming it, even though Mimi is probably not going to say that.
"I had no clue she'd hit my ball. We just heard everyone shout."
Besides setting some sort of record for holes in one, Kyriacou had a highly satisfactory final day, with five birdies in her 71. It left her four-under and with a share of eighth place.
"I think I've learned a lot in majors," she said, "which I'll take into next year."
Asked about probably being in the world top 10, and the top-ranked Australian, she said; "There's nothing wrong with friendly competition, but I haven't got the win just yet. So when I do that, I'll be a little bit more arrogant, I think."
Yamashita won by two shots to claim the first major of her career after keeping England's Charley Hull and Japan's Minami Katsu at bay.
Yamashita finished 11-under after she sank three birdies on the front nine and remained steady on the back nine, until a late stumble with her first bogey on the par-four 17th.
Hull mounted a spirited challenge with five birdies that brought her to within one shot of Yamashita. However, back-to-back bogeys on the 16th and 17th sealed her fate.
Katsu also tied for second with a final-round score of 69.
Australia's Minjee Lee finished with a level-par 72 to end two-under-par and with a share of 13th place.
"I feel like that's probably the worst score I could have had today. I felt like I was going pretty well and then just kind of made a silly mistake on 14," she said.
"It was one of those weeks where I was kind of in the middle, like I wasn't really amazing at one thing or another. I'm not complaining, but I would have liked to be in the top 10."
Having won the KPMG Championship, her third major title, Lee said she is pleased with her year overall.
"I think, from where I was at the beginning of the year, obviously winning KPMG and played Chevron and had a good finish at Evian and all right at US Open and all right here. So I feel like I've done pretty well. Maybe an 8.5."
Earlier, the third Australian, Grace Kim, ended her British Open with a dispiriting 80 to slip to 12-over-par.
Lydia Ko, New Zealand's defending champion, ended on three-over for a share of 36th place, alongside world No.1 Nelly Korda, among others.
With agencies
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