Laura Robson could not build on Wednesday's win over Heather Watson as she went out of the Aegon GB Pro-Series Barnstaple to Ekaterina Bychkova.
The Londoner, 17, had treatment on her foot in the early stages and Russia's Bychkova won the quarter-final 6-4 6-4.
Robson, currently ranked 135, is still set to reach a career-high next week.
Fellow Briton Anne Keothavong continued her fine recent run of form by beating Switzerland's Stefanie Voegele 6-3 7-6 (7-4) to reach the semis.
Keothavong twice failed to serve out the match in the second set but prevailed in the tie-break to set up a semi-final meeting with top seed Mona Barthel.
The British number three has been enjoying a fine end to the season, coming through qualifying to reach the main draw at WTA events in Austria and Luxembourg earlier this month, and reaching the semi-finals at the latter.
Barnstaple is part of the second-tier ITF circuit and marks the end of the season for many players.
British number one Elena Baltacha is absent from the competition as she opts to finish her competitive year at the ITF event in Poitiers, France.
Baltacha is through to the quarter-finals after beating local favourite Virginie Razzano 6-4 6-4 and now plays Magda Linette.
"That was a very big win for me," she said. "I've lost to her in the past because she beat me mentally but not today. I was much stronger and I just felt so focused and in the moment. That was a really amazing feeling.
"It's been a good season for me and I'd like to end it on a high note so performing well against a quality opponent like Virginie, in front of her home crowd, gives me a lot of satisfaction and lots of confidence as well."