Keothavong has reached the third WTA Tour semi-final of her career
Britain's Anne Keothavong suffered a heavy defeat by Caroline Wozniacki in the RMK Championships semi-finals as her fine run came to an abrupt end.
The 25-year-old fell to a 6-1 6-0 loss against the top seed in less than an hour in Memphis.
"I just played terribly. It's the worst I played all week," said Keothavong, who is still expected to break into the world's top 50 next week.
"When you get to a semi-final, that's not how you want to play."
Keothavong was attempting to reach her first WTA final, and become the first British woman to do so since Jo Durie in 1990.
But the Londoner found herself hopelessly outgunned by Wozniacki as she received a harsh lesson from a player ranked 40 places above her.
"It was just one of those days where nothing was working," added Keothavong.
"But, you have good days and bad days - this was definitely a very bad day."
Despite her defeat, Keothavong - currently at 52nd in the world - is almost certain to move into the top 50 when the new rankings are announced on Monday.
Britain has not had a woman in the top 50 since Durie back in 1993.
Wozniacki will meet second seed Victoria Azarenka in the final - after the latter's 6-4 3-6 7-6 (7-1) victory over Germany's Sabine Lisicki.