Britain's Emma Raducanu lost in the first round of the Abu Dhabi Open as she went down in straight sets to former Wimbledon champion Marketa Vondrousova.
Raducanu, 22, was beaten 6-3 6-4 as she proved unable to take advantage of her late wildcard entry to the main draw.
She made a positive start against Czech Vondrousova and led 3-1 after an early break of serve, but she then surrendered the first set by losing five consecutive games.
Vondrousova, who returned from a six-month lay-off in January following shoulder surgery, saved four break points early in the second set before breaking for a 5-3 lead and the chance to serve out the match.
While Raducanu offered an immediate response to stay in contention by winning the next game, the 2021 US Open champion's hopes of making a comeback were soon ended.
It was all over when Vondrousova, the 2023 winner at Wimbledon, clinched her third match point.
Raducanu was promoted into the main 28-player field in Abu Dhabi at the weekend, having initially been set to compete in qualifying for the first time since her fairytale run in New York three and a half years ago.
The world number 56 reached the third round of the Australian Open last month. She climbed back into the world's top 60 last year after missing most of the 2023 season following surgery on both wrists and her left ankle.
Vondrousova will play Kazakh fourth seed Yulia Putintseva next.