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 when trailing 3-0 in the second set after claiming the first in a tiebreaker.

Collins reaches her second semi-final of the year and will play the winner of the late match between Venus Williams and Maria Sakkari.