Emma Raducanu is out of the Ostrava Open after losing to fifth seed Daria Kasatkina in the first round.
The 19-year-old lost 7-5 6-4 against Russian world number 11 Kasatkina.
The defeat comes after British number one Raducanu retired injured from her Korea Open semi-final against Jelena Ostapenko on 24 September.
Raducanu has struggled with injuries during her first full year on the WTA tour as she seeks to build on her 2021 US Open victory.
Kasatkina will play fellow Russian Ekaterina Alexandrova in the next round.
But there was British success elsewhere for Dan Evans and Harriet Dart.
Evans beat Moldova’s Radu Albot 6-7 (3-7) 6-1 6-4 at the Rakuten Open in Tokyo while Dart beat Spain’s Nuria Parrizas-Dias 6-2 6-4 at the Jasmin Open in Tunisia.
There was also a shock defeat for world number one Carlos Alcaraz at the Astana Open in Kazakhstan.
Belgian David Goffin won 7-5 6-3 to hand 19-year-old Alcaraz his first straight-set defeat of the season.
“I always believe that I have the level to cause some trouble against those guys,” said Goffin, whose world ranking is 66.
“When you play against the world number one on a big stage, big crowd, the fire inside gives you so much power to play your best tennis because you don’t have any choice.
“You have to fight and give your best and that was the case today.”