Serena-slayer Johanna Konta has been sent packing from the WTA's Silicon Valley Classic after suffering a 7-6 (4) 6-3 quarter-final loss to fourth seed Elise Mertens.
The Briton had opened the tournament with a bang on Tuesday when she shocked 23-time grand slam champion Serena Williams 6-1 6-0, the worst loss of the American great's career.
Konta was unable to recreate the magic, however, instead squandering a 5-2 lead in the opening set against the Belgian before bowing out meekly.
Mertens, bidding for her fourth title of the year, now moves into a semi-final against fifth-seeded Romanian Mihaela Buzarnescu.
American Danielle Collins also moved into the semis when former world No.1 Victoria Azarenka retired injured early in the second set after claiming the first in a tiebreaker.
Azarenka grabbed her right leg in the opening game of the second set, lost the first three games and was evaluated by a trainer and doctor before retiring prior to the fourth game.
Collins reaches her second semi-final of the year and will play Maria Sakkari, who upset third-seeded Venus Williams 6-4 7-6 (2) on Friday.
Sakkari's win was all the more impressive after she came back from 0-3 down in the first set and 3-5 behind in the second set.