Emma Raducanu was bundled out of the Washington Open in a 6-4 6-3 semi-final defeat to Anna Kalinskaya.
The British number one matched the Russian early, using her superior serve to pick up five aces. However, she was frequently unable to take full advantage of her firepower as she failed to convert any of her four break point opportunities.
This left enough of a window for Kalinskaya to capitalise, clinching the first set before cruising through the second and wrapping up the victory in one hour and 34 minutes.
Kalinskaya will play Leylah Fernandez in Sunday's final after the the Canadian edged out third seed Elena Rybakina in a marathon encounter that required three tie-breaks to be resolved.
Fernandez prevailed 6-7 7-6 7-6 after three hours and 12 minutes on court.
Meanwhile, a scrappy performance from Australia's Alex de Minaur was enough to book him a spot in the men's final with a 6-4 6-3 victory over French lucky loser Corentin Moutet.
The world number 10 overcame 33 unforced errors to wrap up the win in one hour and 44 minutes.
He will face Spain's Alejandro Davidovich Fokina in the final, after the 12th seed upset American fourth seed Ben Shelton 6-2 7-5.
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