Two-time champion Andy Murray suffered a straight-set loss to Dusan Lajovic in the first round at the Miami Open.
Former world number one Murray, winner in both 2009 and 2013, was beaten 6-4 7-5 by the 76th-ranked Serb.
It comes a week after the fatigued 35-year-old Scot lost to Jack Draper in the third round at Indian Wells.
Fellow Briton Kyle Edmund is also out after losing 7-5 7-5 to Wu Yibing, while Emma Raducanu was defeated in the women's draw by Bianca Andreescu.
Murray, currently 52nd in the world, won a remarkable seven deciding sets among several marathon victories in an exhausting opening to his 2023 season.
But he was unable to produce the response required after Lajovic, 32, forced the first break of serve in game seven and went on to clinch the opening set.
Murray hinted that another memorable comeback could be on the cards as he broke back immediately to stay in the second set at 5-5.
However, Lajovic moved quickly to extinguish those hopes with another break and was relieved to serve out the match in straight sets when Murray framed a forehand.
"When I didn't close it out I thought it's happening again," Lajovic, who will play American Maxime Cressy, said of Murray's ability to battle back.
It is a disappointing result for Murray, who had not lost in the opening round of a tournament since early January, and he is now 8-5 overall this season.
"Some days you obviously don't hit the ball your best, but my movement wasn't great today," Murray said.
"I served pretty well, but the rest of the game was a bit of a problem."