Ten minutes is the standard length of a tennis warm-up and the time it takes to change the sightlines from within the world's most prestigious Centre Court.

Andre Agassi and Steffi Graf will raise the roof at Wimbledon next month and today the All England Club announced its new retractable roof is on schedule for its formal unveiling on Sunday, May 17.

The new roof comes complete with lights, which means Centre Court matches at Wimbledon could be night-time spectacles.

"We could finish after 10 o'clock in the evening," Wimbledon chairman Tim Phillips said. "The scheduling will still be the same as an outdoor day time event, but there is no absolute cut-off time. The players will have to come off court when the roof closes. Ideally that would be at the end of a set rather than 8-8 in the final set."

The All England Club would not set a definitive cut-off time for Centre Court matches' instead Phillips said officials will make a judgement call on a match-by-match basis.

"It's difficult to forecast all the circumstances that could arise, so we won't talk about a last time a match could finish," Phillips said. "We will try to make a judgement call. Sometimes you won't get it right but we'll try to most of the time."

Just how wide is the roof?

It would take about 7,500 umbrellas to provide the shelter the retractable roof provides over Centre Court. One hundred percent of the fabric roof is recyclable and with the roof closed the area inside Centre Court is large enough to house about 290 million tennis balls.

A trio of former World No. 1 players — Agassi, his wife Graf and Kim Clijsters — will join Tim Henman to play the first tennis match under Wimbledon's new Centre Court roof as part of A Centre Court Celebration next month.

Final testing of the roof and air-management system is being carried out now.

The air-management system has a vital role in controlling and stabilising the internal environment within the bowl — controlling humidity and preventing either condensation on the inside of the roof or sweating of the grass — either of which would make the court slippery and unsuitable for play, the All England Club said in a statement.

"We set out to make Wimbledon the world’s premier tennis event; the tournament the players most want to win, the tournament spectators most want to come to and the tournament everyone wants to watch," Ian Ritchie, Chief Executive of the All England Club said today. "The new Centre Court roof project has been a sophisticated engineering feat.  Much of the testing is complete and we are now making final adjustments ahead of the Centre Court Celebration event on May 17.  That event is an important part of the testing procedure and will enable us to see how both the roof and air-management system actually perform under live conditions with a capacity crowd."

There are 10 trusses that hold the retractable roof, which takes a maximum of 10 minutes to close. A maximum of about 30 minutes is expected before play can start or resume after the roof is closed and the internal environment is controlled and stabilized. The roof will be formally tested under match conditions at next month's exhibition.

The exhibition event, which will feature a men's singles, ladies singles and a mixed doubles match, is designed to test the new roof  and air management system with live tennis in front of a capacity crowd of 15,000.

"There is no tennis venue more special to me than Centre Court at Wimbledon," Graf said. "It just doesn't get any better. I couldn't be more honored to play there again with my husband Andre, and tennis greats Kim and Tim. It will mean so much to return to Wimbledon and see so many familiar places, relive so many wonderful memories."

All three matches will be played under a pro-set format — first to 8 games with a tie breaker played at 8-8.   The exact order of play will be confirmed in the coming weeks.

"I am honored to be invited by the All England Club to take part in this landmark occasion," Agassi said. "I have great memories of playing at Wimbledon and to be amongst the first to play under the new Centre Court roof is really exciting."

Gates will open at noon on Sunday, May 17 with play scheduled to start at 2:30 p.m.

"Wimbledon’s Centre Court was always a special place for me and it’s just great to have the chance to play there again with the likes of Andre, Steffi and Kim," Henman said. "I think it will be a really fun day for everyone and the new roof is going to make it a fascinating experience."

In their lone professional meeting, Graf swept Clijsters, 6-2, 6-2, in the 1999 Wimbledon. 

"To be asked to be part of this unique event with Andre and Steffi and Tim is very exciting and a real privilege. It has been ten years since I played Steffi at Wimbledon," Clijsters said. "My first and only match against her in my career.  It was quite an experience.  I was very nervous to play against my idol and because of the rain the match took two days to finish.  The new roof will prevent that this time around."

"We set out to make Wimbledon the world’s premier tennis event.  The new retractable Centre Court roof, and air management system, is another important part of The Championships’ progression and will guarantee the play that today’s audiences expect," Ritchie said. "Though this project has been a sophisticated engineering feat, we always wanted to capture the essence of Wimbledon’s history and tradition in a new, modern Centre Court which itself would still be celebrated as the stage of some of the most memorable moments in tennis. With players of the caliber of Agassi, Graf, Clijsters and Henman this test event promises to be hugely entertaining.  Brilliant players, great tennis, an iconic venue and the chance to be part of Wimbledon history – what more could one want?"