In Birmingham Classic, Belgian top seed 25-year-old Elise Mertens was beaten 7-6 (7-5) 6-7 (5-7) 7-6 (7-4) by Australia’s Ajla Tomljanovic.
But second seed Ons Jabeur advanced, with the 26-year-old Tunisian beating America’s Caty McNally 6-4, 6-2 on her debut at the tournament.
Towards the end of the day, Russian fourth seed Daria Kasatkina had to come from a set down against Slovenia’s Polona Hercog to win 4-6, 6-3, 6-3 to make it three out of the top four seeds to advance.
In doubles, Heather Watson and Harriet Dart were beaten by fellow Briton Naiktha Bains and Czech Tereza Martincova 4-6, 6-3, 10-5 in the first round.
Watson, 29, is still in the singles and faces fifth seed Zhang Shuai for a spot in the quarter-finals.