LONDON - AN air of anticipation hung heavy over Wimbledon on Friday with fans clutching precious Centre Court tickets praying for rain.

After four days of unbroken sunshine, menacing thunder clouds gathered over the All England Club and this was greeted with glee by many of the 15,000 fans filing in to take their seats in the hallowed arena.

Roger Federer and Novak Djokovic should have been the main attractions on Friday but some spectators were more interested in being the first to see a competitive match played under Wimbledon's new multi-million pound Center Court roof.

Serena Williams also came prepared for a wet day in southwest London as she walked out on Court Two wearing her customised white raincoat.

However, the American did not need it as she breezed into the fourth round with a 6-3 6-4 win over Italy's Roberta Vinci.

While fans on the outside courts were delighted the heavy thunder showers forecast did not materialise during the first few hours on Friday, Centre Court occupants hoped the unpredictable British weather was true to form.

'Usually when I buy my ticket through the ballot, I'm always praying that the weather doesn't spoil my day because I come down from Nottingham,' Chloe Marshall said.

'This time, I really want to see rain today as then I can tell everyone for the rest of my life I was one of the first to see the roof in action.'

Joshoda Batra from London was also hoping to earn bragging rights.

'We got dressed thinking it might rain today and it would be great to be the first to see the roof,' added Batra as she folded away a newspaper announcing the death of singer Michael Jackson on its front page.

Like the rest of the world, Wimbledon was rocked by the unexpected death of Jackson on Thursday.

'Oh my lord... Michael Jackson died... RIP sad and surreal. Regardless of what you think of him he was completely revolutionary and will be missed,' men's sixth seed Andy Roddick said on his Twitter page. -- REUTERS