Heather Watson saw her Sony Open Tennis challenge ended in the opening round with a straight-sets defeat to French qualifier Virginie Razzano.
The 21-year-old Briton, who was a wild card in Miami, had reached the second round in Indian Wells two weeks ago - including a victory over Razzano during qualifying - but was unable to match that as she fell to a 6-4 6-0 loss in 71 minutes.
Ranked 40 places lower than her opponent at 121 in the world, Watson gained the edge in a nervy opening to take a 3-1 lead, only for Razzano to reel off the next three games.
Watson broke again to level at 4-4 but errors continued to creep into her game and the Frenchwoman scored the decisive break in game nine before holding to see out a topsy-turvy first set in 43 minutes.
The Briton's game then crumbled in the second set, which was wrapped up with very little fuss by Razzano.
Double faults and a poor shot selection failed to help Watson, whose first-serve percentage was just 14 while her only two break-point opportunities were brushed aside before the Frenchwoman clinched the contest on serve and with her first match point.
In the day's other games, Croatian teenager Donna Vekic beat Japan's 43-year-old Kimiko Date-Krumm 7-6 (7-2) 6-2.
The evergreen Asian veteran reaching the Miami final in 1995 - 15 months before her 17-year-old opponent was even born.
Vania King demolished Estrella Cabeza Candela 6-0 6-0, Lauren Davis ousted China's Shuai Zhang 6-2 6-3 and Coco Vandeweghe beat Marina Erakovic 6-4 7-6 (8-6).
Nadia Petrova made the most of a wild card by beating Urszula Radwanska 7-5 1-6 6-4 and Germany's Andrea Petkovic was a 6-3 6-4 winner against Spaniard Maria-Teresa Torro-Flor.
Christina McHale overcame Jie Zheng 6-4 6-2, Alison Riske came from a set down to beat Nadiya Kichenok 1-6 7-5 6-2 and Madison Keys cruised past Estonian wild card Anett Kontaveit 6-3 6-2 in the final match of the night.