19-year-old Canadian Leylah Fernandez caused another surprise two days after her win against Angelique Kerber and reached the semifinals of the US Open.
The number 73 in the tennis world rankings won on Tuesday at the Grand Slam tournament in New York against the fifth seeded Ukrainian Jelina Switolina 6: 3, 3: 6, 7: 6 (7: 5).
Fernandez had previously defeated the defending champion Naomi Osaka from Japan and the former tournament winner Kerber.
In the semifinals, Fernandez will meet Aryna Sabalenka from Belarus or the Czech Barbora Krejcikova.
The tennis world number second Daniil Medvedev is the first semi-finalist in the men's competition at the US Open.
The 25-year-old Russian finished the winning streak of the Dutch qualifier Botic van de Zandschulp of the same age at the Grand Slam tournament in New York on Tuesday.
Medvedev prevailed against the 117th in the world rankings 6: 3, 6: 0, 4: 6, 7: 5.
Van de Zandschulp made it to the quarter-finals for the first time in one of the four most important tournaments.
In the fight for a place in the final, Medvedev will face the number twelve seeded Canadian Felix Auger-Aliassime or Carlos Alcaraz from Spain.
The 18-year-old Alcaraz had defeated Munich's Peter Gojowczyk in the round of 16 and is the youngest male quarter-finalist at the US Open in the history of professional tennis since 1968.