Emma Raducanu has revealed that she had booked her flights back to the UK a fortnight ago, having never expected to make it so far in the US Open.
The 18-year-old beat Swiss Olympic gold medallist and world number 11 Belinda Bencic 6-3, 6-4 to reach the last four at Flushing Meadows.
She will face Greek 17th seed Maria Sakkari in the semi-finals, which will be played from midnight BST on Friday.
Raducanu said she has “just been focusing on one day at a time”.
“When you’re playing tournaments, you just get into this sort of auto-pilot mode of your routines, recovering on the day off in between,” she said.
Raducanu was ranked outside the top 350 in June but is now expected to rise to at least 51 in the world on Monday and become Britain’s number one player – ahead of Johanna Konta and Heather Watson.
“I didn’t expect to be here at all,” she said.
“I think my flights were booked at the end of qualifying, so it’s a nice problem to have.”
She said she is “just really enjoying the experience” and added: “Out there on the court today, I was saying to myself, ‘This could be the last time you play on Ashe, so might as well just go for it and enjoy everything’.”
Raducanu is one of two teenagers into the last four in New York after matching Canada’s Leylah Fernandez, 19, who has enjoyed her own breakout tournament.
Reflecting on her quick rise to prominence since her tour-level debut in June, she said: “I mean, I didn’t compete for 18 months, but here I am, and it just shows that if you believe in yourself, then anything is possible.”
She said she did not want to get distracted thinking about the trophy: “I don’t want to get ahead of myself at all.
“If I take care of what I can control, then that’s going to give me the best chance.”
She said she focuses on winning one point at a time: “It’s got me to this stage, and I’m not going to change anything.”
Bencic was the first top-30 opponent Raducanu had faced, and despite trailing 2-0 in the first set, she quickly took control as the match progressed.
Raducanu said once she got used to how “aggressive” Bencic was on the court, she did not over-press as much.
“I found a way to win, but it was very difficult to play against someone at such a high level,” she said.
She said her “calmness” and “mental strength” comes from her upbringing.
She was born in Toronto in 2002 to a Chinese mother and Romanian father and the family moved to England when she was two.
“My parents have both instilled in me from a very young age to definitely have a positive attitude on court, because, yeah, when I was younger, it was definitely an absolute no-go if I had any sort of bad attitude,” she added.