Emma Raducanu said she "struggled with everything" as she was beaten by world number 30 Anhelina Kalinina in the first round of the Qatar Open in Doha.
The Briton was well below per in a one-sided first set, hitting 15 unforced errors to her Ukrainian opponent's two.
She saved two match points in a far more competitive second but Kalinina came through to win 6-0 7-6 (8-6).
"I was struggling with everything - serve, return, forehand, backhand," Raducanu, 21, told Sky Sports.
"I felt like I never really got into it."
The former US Open champion is in the early stages of her comeback after missing most of 2023 following surgery on both of her hands and left ankle.