Emma Raducanu was knocked out of the Miami Open by Canada's Bianca Andreescu after a thrilling first-round match that showcased the huge potential both players still possess.
The British number one, 20, lost 6-3 3-6 6-2 against 22-year-old Andreescu, who also won the US Open as a teenager.
A tight contest ran away from Raducanu when Andreescu won the last four games.
Two more Britons - Andy Murray and Kyle Edmund - play in the first round of the men's singles later on Wednesday.
Former world number one Murray, 35, plays Serbia's Dusan Lajovic about 21:00 GMT, while Edmund continues his comeback from a knee injury against China's Yibing Wu at a similar time.