Former Wimbledon finalist Agnieszka Radwanska suffered a shock defeat by Romania's Monica Niculescu in the semi-finals of the Nottingham Open.
The Polish world number 13, seeded first, lost 5-7 6-4 6-0 to an opponent ranked 48 places below her.
It continues a poor year for Radwanska, who has not made a single final and has seen her ranking fall seven places.
Niculescu will now play 17-year-old Ana Konjuh who beat fifth seed Alison Riske 6-4 6-3 to reach her first WTA final.
Croatia's Konjuh was playing her second match of the day because of rain delays at the tournament, having earlier completed her quarter-final.
The final, which had been scheduled for Sunday, takes place on Monday at 11:00 BST, with the winner lifting the inaugural Elena Baltacha Trophy, named in honour of the late British tennis star who died last year at the age of 30.