Russia’s Anastasia Pavlyuchenkova has questioned the bias of the officials at Wimbledon after controversial calls during the fourth-round contest against Britain’s Sonay Kartal.

Wimbledon organizers have apologized and explained that “human error” was the reason behind the electronic line-calling system being turned off during a match on Sunday.

It’s been another incredible run for Kartal, who reached the third round last year before falling bravely to Coco Gauff. Another victory today at SW19 would see the world No51 vault above both Katie Boulter and Emma Raducanu to become the new British women’s No1.