The Duchess of Cambridge shared a heartfelt congratulations to tennis teen sensation Emma Raducanu as she became the first qualifier to reach a Grand Slam singles final.

The 18-year-old, who only graducated school this summer, made history on Thursday by earning a place in the US Open final after her triumph over Maria Sakkari in New York.

The teenager is the first British woman to reach the final at Flushing Meadows since Virginia Wade won the title 53 years ago. Tomorrow she faces fellow teen, Canadian world Leylah Fernandez, 19 (who is ranked 73rd in the world).

Kate Middleton signed her tweet with the letter “C” (for Catherine), as she retweeted Raducanu’s own social media message with one of her own: “What an incredible achievement at this year’s US Open. We will all be rooting for you tomorrow.”

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Reacting to her win, Raducanu told the BBC, “It obviously means a lot to be the first in the final for so long. Crazy, cool. To be here in New York for three weeks is just absolutely mind-blowing for me.”

She added, “Honestly, right now I’m just thinking of the game plan, how to execute. That’s what’s landed me in this situation. It hasn’t been focusing on who’s expected to win this match or that one. I think it’s just taking care of the day. That’s what I’m doing quite well at the moment.”

“I don’t feel any pressure to win. Any pressure is self-inflicted. I have expectations of my level and how I want to perform but there’s no pressure in terms of results.”