Wimbledon organisers are set to extend the tournament into a third week because torrential rain is expected to fall on SW19 tomorrow. Met Office forecasters believe that there is a 90 to 100 per cent chance of heavy downpours, which would force the men's final to be postponed until Monday and leave tournament officials with a bill for £1million in ticket refunds.

Stephen Holman, a Met Office forecaster, said: “Predictions for Sunday are bad. It will almost definitely be wet, with showers that could last throughout the afternoon.”

Tickets for the show courts are sold out this weekend. Laura Robson, the 14-year-old who hopes to become the first Briton since Annabel Croft, in 1984, to take the girls' singles title, will play Noppawan Lertcheewakarn, of Thailand, on No1 Court today.

Fans are paying upwards of £350 a ticket on eBay in a bid to see Roger Federer try to beat Bjorn Borg's record of five consecutive men's singles victories at the tournament tomorrow. But the bookmakers are sure that those who splash out on tickets for the match will be left disappointed and have slashed the odds on there being no play between Federer and Rafael Nadal to 6-4. If there is less than an hour's play, a full refund will be paid. If there is less than two hours, 50 per cent of the price will be refunded.