Raducanu effectively overtook Boulter with her victory over Naomi Osaka, the four-time major winner, in the second round in Washington. It followed a similarly impressive victory over the seventh-seeded Ukrainian Marta Kostyuk in Raducanu’s first match.

Emma Raducanu beats Maria Sakkari to reach final four in Washington ahead of next months US Open; watch Raducanus semi-final at the Mubadala Citi DC Open live on Sky Sports Tennis on Saturday

Emma Raducanu has made a worrying admission ahead of her semi-final clash against Anna Kalinskaya at the Washington Open on Saturday. The British tennis star has reached the last four at a WTA Tour event for the first time this year and has been in brilliant form at the American tournament.