Some tennis fans got a lesson in drinking etiquette this weekend.

A Wimbledon umpire warned London spectators against opening Champagne bottles during serves after an unfortunately-timed uncorking disrupted a singles match between Russian players Anastasia Potapova and Mirra Andreeva on Sunday.

During the match, Potapova began a serve against Andreeva when a Champagne pop interrupted her toss, according to the Associated Press. The serve landed out of bounds, and after Potapova lost the point on her second serve, the match’s umpire addressed the crowd.

“Ladies and gentlemen, if you are opening a bottle of champagne, don’t do it as the players are about to serve,” Australian umpire John Blom announced, which was met with chuckles from attendees. In the video, Potapova is seen nodding along to the announcement.

On-premise announcers playfully called it “the most Wimbledon warning ever.” The 2023 Wimbledon championship, held at the All England Club in London, runs from Monday, July 3 to Sunday, July 16.