As pointed out elsewhere, the Korean operates under the handicap of having to play on three consecutive days, something no other finalist in this competition will have to do. We'll see how it affects her.
She came out with a thoroughly German program, and it was the best-chosen recital program we've heard since Eduard Kunz' in the prelims. She started out with Egon Petri's transcription of Bach's Sheep May Safely Graze. (Fifty years ago this year, Petri made a recording of Busoni's Fantasia Contrappuntistica, and I heard it in college and was blown away by both the pianism and the piece.) She turned this into a pretty Late Romantic confection and then, without an applause break, went straight into two of Schubert's impromptus from D. 935, in B-flat major and F minor. These were also excellent, with the B-flat major played effervescently. Her powdered-sugar approach isn't for all tastes, but she does it extremely well.
Better still, she can do other things too, as she showed in her performance of Beethoven's Sonata in C minor Op. 111. This was the best late-Beethoven performance I've heard so far in this competition. The lengthy second movement was especially well done, with the majestic chords at the beginning played with unwavering rhythm but varying intensity depending on the moment, then giving way to the syncopated figurations that Son played with jazzy verve. The piece builds to a series of trills, and she rendered them in exhilarating fashion. (Not that this should win her the competition, but she's the best triller in the field.) Ending a recital with late Beethoven was a gamble that paid off for her.