Johanna Konta saw her Monterrey Open bid end with a 6-3 6-4 semi-final defeat against Czech Marie Bouzkova.
The 28-year-old world number 16 was contesting her first semi-final since June's French Open, and had reached the last four after saving two match points against Anastasia Potapova on Friday.
Bouzkova, 21, ranked 41 places below second seed Konta, took the first set after breaking in the sixth game.
In her first meeting with the Briton, she won in an hour and 41 minutes.
The ninth seed will play top seed Elina Svitlova or Arantxa Rus of the Netherlands in Sunday's final.