Organizers of this year’s Wimbledon have said a ball boy caused the latest error with the electronic system that has replaced the traditional line umpires at this year’s tournament.

The incident occurred in Tuesday’s quarterfinal between American Taylor Fritz and Russian Karen Khachanov. With Fritz serving in the fourth set, the system called “fault” mid-point, forcing umpire Louise Azemar-Engzell to intervene.

After making a phone call, Azemar-Engzell asked for the point to be replayed “due to a malfunction.”

In a statement to CNN Sports on Wednesday, the All England Lawn Tennis and Croquet Club (AELTC) said the electronic system had not recognized the start of the point.

“The player’s service motion began while the BBG (ball boys and girls) was still crossing the net and therefore the system didn’t recognise the start of the point,” it said. “As such the Chair Umpire instructed the point be replayed.”