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.

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.

Though Wimbledon’s ancient courts are no stranger to drama, this year’s fourth-round match between Anastasia Pavlyuchenkova and Sonay Kartal has set off a discussion that won’t easily quiet down. Though the Russian veteran finally triumphed with a 7-6,