Katie Boulter was beaten in straight sets by Italy’s Camila Giorgi in the first round at Indian Wells.
Two days on from her victory at the San Diego Open, the Briton fell to a 6-3 6-2 defeat by world number 106 Giorgi.
The Italian, who has four WTA singles titles to her name and has been ranked as high as 26th in the world, needed just 78 minutes to wrap up victory.
In the men’s draw, Briton Jack Draper also lost in the first round – 1-6 6-3 6-2 to Australia’s Chris O’Connell.
Boulter was unable to back up the biggest win of her career in San Diego as she was broken in her first two service games against an inspired Giorgi who eased to the first set.
Giorgi surged into a 4-0 lead in the second and although there was some resistance from Boulter as she twice threatened to break, the Italian served out for victory.
Meanwhile, Draper was unable to capitalise on a good start which saw him take the first set against O’Connell convincingly.
The Australian, ranked 66 in the world, forced a decider and although Draper broke early in the third, O’Connell reeled off six straight games to advance to the second round.
Elsewhere, Andy Murray faces Belgium’s David Goffin in the first round, while Cameron Norrie has received a bye and Emma Raducanu plays qualifier Rebeka Masarova.