Wimbledon could witness its first final to be played indoors after rain started falling in south-west London just 75 minutes before the start of the women's showpiece on Saturday between Venus and Serena Williams.
Covers were pulled on Centre Court at 1145 GMT after it started to drizzle.
Organisers are likely to wait up to 40 minutes before the American sisters are due to walk on court at 1300 GMT before deciding whether to close the new retractable roof over the hallowed turf.
Once the translucent canopy is pulled over, it takes up to 40 minutes to acclimatise the arena and ensure the grass does not sweat.
The sisters, who between them own seven Wimbledon singles titles, warmed up by hitting with male practice partners on adjacent outside courts on Saturday morning.
Five-times champion Venus was seen pounding down her thundering serves while US Open and Australian Open holder Serena opted to hone her groundstrokes.