by Tom Pilcher

LONDON - After four days of glorious sunshine, Wimbledon might finally get the chance to show off its latest innovation with rain forecast for the first time at this year's championships on Friday.

So far the Centre Court roof, estimated to have cost £80 million (S$190 million), has only been used to shade the dignitaries in the royal box but that may be about to change.

World number two Roger Federer is first up on the revamped court where he has a third-round match against German 27th seed Philipp Kohlschreiber, a dangerous opponent who famously beat American Andy Roddick in the 2008 Australian Open third round.

'I'm definitely looking forward to my first time under the roof,' the 14-time grand slam winner told reporters.

'I don't know if it's gonna be this year, but I'll stick around and get an opportunity. We'll see.'

Noisy women's eighth seed Victoria Azarenka of Belarus follows against 28th-seeded Romanian Sorana Cirstea and late in the day Serbian fourth seed Novak Djokovic will need his A-game to edge past American Mardy Fish, also seeded 28.

Women's second seed Serena Williams, hunting for her 11th grand slam title, has been demoted to Court Two and will open up against unseeded Italian Roberta Vinci.

The other highlights are likely to come from Court One, with five seeds, including Russian Elena Dementieva (4), France's Jo-Wilfried Tsonga (9) and Croat Marin Cilic (11), in action.

Maria Sharapova's conqueror, Argentine Gisela Dulko, faces 10th seed Nadia Petrova of Russia on Court Three, while doubles partners Ai Sugiyama of Japan and Slovakian Daniela Hantuchova will do battle in the singles on Court 18.

'It's a secret,' a smiling Sugiyama told reporters when asked what she would do to beat her familiar opponent.