Heather Watson was unable to clinch victory for Great Britain at the first time of asking in their Billie Jean King Cup play-off tie against Mexico.
However, the world number 68 lost 6-3 7-6 (7-1) in London to an opponent ranked 138 places below her.
Katie Boulter can seal victory against Giuliana Olmos later on Saturday.
If Boulter also loses, the tie will go to a deciding doubles match.
The second singles match will take place at 16:15 BST, with the day's play at the National Tennis Centre paused to mark the funeral of Prince Philip.