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.