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.
She won one match in Auckland in her first tournament back, reached the second round of the Australian Open and beat world number 36 Marie Bouzkova in Abu Dhabi last week.
But that win was followed by a comprehensive defeat by second seed Ons Jabeur and, having been given another wildcard this week in Qatar, she suffered another early exit.
Raducanu had a set point at 6-5 on her serve in the second-set breaker but Kalinina saved it and took the next two points to seal victory.
The Briton hit 48 unforced errors compared to 22 by Kalinina, who will play eighth seed Jelena Ostapenko next.
"It was combination of things," Raducanu said.
"It was my first day-match I have played in a year. That is different.
"I need to practise training outside a bit more. The lights, conditions, shadows... it is really hard to see the ball, I found towards the end.
"When my tennis isn't there I have to try and at least fight and I did that in the second set."
Raducanu said she will now return home after consecutive weeks on tour but said she needs to "schedule my tournaments a bit better".
"I just struggled with the timing of the ball," she said. "It will come with more time practising as well as matches.
"It is hard for me to get used to the tour schedule. It is one tournament then another straight away.
"I need to schedule my tournamnerts a bit better and try to get more matches under my belt."
