Watson failed to capitalise on two chances to seal the second set
Heather Watson and Anne Keothavong suffered defeat in the first round of qualifying at the BNP Paribas Open in Indian Wells on Monday.
Watson, from Guernsey, lost out to world number 104 Kirsten Flipkens from Belgium in straight sets.
The 18-year-old, who is ranked 132, went down 6-2 7-6 (7-4) after twice failing to serve out the second set.
Keothavong, 27, lost 6-4 6-1 to Puerto Rican wild card Monica Puig, who is ranked more than 300 places below her.
Watson was handed a boost with the news that she has been awarded a wildcard for the main draw of the Sony Ericsson Open, which begins in Miami on 22 March.