British number one Heather Watson was knocked out in the first round of the Prague Open by Slovenia's Polona Hercog.
Watson lost 7-5 3-6 7-6 (7-5) to world number 72 Hercog, 24, in a match lasting more than three hours.
The 22-year-old, who won her second WTA title in January, was 3-0 up in the final-set tie-break but was broken three times by her opponent.
Watson also exited her last tournament - the Family Circle Cup - in round one.