Wimbledon will have play on its middle Sunday for the first time since 2004 as tournament organisers battle to deal with a backlog of matches.
The situation became more serious on Friday as a rain-disrupted afternoon and evening saw the schedule badly hit.
Heavy rainfall on Tuesday and Wednesday had already caused the schedulers a major headache that they hope will be relieved by the extra day's play.
Wimbledon announced on Twitter: "There will be play on Middle Sunday. Details announced 1pm tomorrow. All tickets to be purchased in advance online, none available on day."
There will be play on Middle Sunday. Details announced 1pm tomorrow.
All tickets to be purchased in advance online, none available on day.— Wimbledon (@Wimbledon) July 1, 2016
A Wimbledon spokesman said the tournament was 78 matches behind schedule, the bulk of which is accounted for by doubles.
However with the threat of more rain on Saturday, it could fall even further off course, necessitating the comfort buffer of an extra day.
It will be another 'People's Sunday', as the extra day's play was described in 1991, 1997 and 2004, with tickets for all courts to be available to the public.
Unlike 12 years ago, when it was a pay-on-the-gate affair for spectators, this time tennis fans will need to buy their tickets online.
The tournament's objective will be to ensure all third-round singles, and as many doubles as possible, are completed by the end of the weekend.
Play on Centre Court has continued through the week, because of the retractable roof that makes it an all-weather stadium.
But elsewhere the tournament has been plagued by showers and occasionally heavy rain.
Andy Murray - on a day off - was forced to abandon his practice session because of the rain, while many players waited in frustration for the dark clouds to clear.