Johanna Konta eased past American Sofia Kenin to reach the quarter-finals of the Silicon Valley Classic.

A day after inflicting the worst defeat of Serena Williams’ career, British number one Konta struck nine aces in a 6-1 6-4 victory.

“I approached the match as a separate challenge,” said Konta, 27. “Every tournament that I go into, I want to be there until the very end.”

Konta will face fourth seed Elise Mertens of Belgium next.

Mertens reached the last eight with a 6-2 6-0 victory over American wildcard Ashley Kratzer.

Konta added: “[Mertens is] a great player. She has been playing very well consistently this season, and that is a big task and she is been doing that so well.”

• Murray continues comeback with win over Edmund
• Live scores, schedule and results

Spain’s top seed Garbine Muguruza withdrew before her second-round match against former world number one Victoria Azarenka because of an arm injury.

Belarusian Azarenka instead faced lucky loser Anna Blinkova, 19, of Russia and needed less than an hour to complete a 6-1 6-0 thrashing. She plays Danielle Collins next.

Boulter heading out? Citi Open results

At the Citi Open in Washington, Britain’s Katie Boulter was 6-4 4-4 down on American Allie Kiick in their second-round tie before play was suspended due to rain.

Sloane Stephens’ preparations for her US Open title defence suffered a setback when she was shocked 2-6 6-4 6-2 by German Andrea Petkovic.

In the men’s draw, former world number one Andy Murray took another big step in his comeback from hip surgery by beating fellow Briton Kyle Edmund 7-6 (7-4) 1-6 6-4 to reach the third round.