The sounds were new to Serena Williams, and the feeling on Centre Court was different. The result, though, was quite familiar.
Playing under the retractable roof for the first time on the court where she's had some of her biggest triumphs, Williams defeated defending champion Petra Kvitova 6-3, 7-5 to reach her eighth Wimbledon semi-final on Tuesday.
"I loved it. I loved the sound,'' Williams said.
"The sound of the balls. It's kind of like a whoosh and a pop. It's really cool. It's almost like a video game, but you're playing. It kind of flies through and you hear it when it lands. ... I really like playing indoor.''
Her game seems well-suited for it.
While rain disrupted play elsewhere at the All England Club, Williams used another commanding serving performance to overpower the fourth-seeded Czech. Williams hit 13 aces - including three in the last game - to end Kvitova's 11-match winning streak at Wimbledon. Her last loss here also came against Williams, in the 2010 semi-finals.
"You can't play a defending Wimbledon champion or Grand Slam champion and not elevate your game,'' Williams said.
"I had to weed out the riffraff and just get serious.''
The American four-time champion seized control by breaking Kvitova for 4-2 in the first set and then never gave her opponent a chance to get back in the match. She saved a set point when trailing 5-4 in the second with a hard serve down the middle that Kvitova could return only into the net. That was the only break point the defending champion earned, as Williams won 86 per cent of the points on her first serve.
"I think that's why she's the great champion, because she knows what she needs to play in the important points,'' Kvitova said.
"It's really tough to beat her.''
Williams, who hit a Wimbledon-record 23 aces in a fourth-round win over Zheng Jie of China, is trying to become the first woman 30 or over to win a Grand Slam title since Martina Navratilova won Wimbledon in 1990. She will face either second-ranked Victoria Azarenka or Tamira Paszek of Austria.
Angelique Kerber advanced to her first Wimbledon semi-final by beating fellow German Sabine Lisicki 6-3, 6-7 (7), 7-5 in a see-saw match also under the roof.
Lisicki, who knocked out Maria Sharapova, saved three match points in the second set and served for the match at 5-3 in the third. But Kerber bounced back to win the last four games, finally converting her fifth match point when Lisicki sent a backhand wide.
| Briton Andy Murray booked his place in a fifth straight quarter-final with his rain-delayed win over Marin Cilic [Reuters]
Outside Centre Court, it was a start-and-stop day at Wimbledon, as the persistent rain continued to cause headaches for organisers.
Play was delayed for about 30 minutes on the outside courts in the morning, and two more rain delays interrupted play for a total of about three hours after that.
Andy Murray and Florian Mayer still found enough time between the showers to wrap up suspended matches and reach the quarter-finals.
In another fourth-round match that was suspended on Monday, Jo-Wilfried Tsonga overcame an ailing back and a one-set deficit to beat American Mardy Fish 4-6, 7-6 (4), 6-4, 6-4.
David Ferrer also advanced in the first match on Centre Court, where organisers again came under scrutiny for their use of the retractable roof.
Their decision to open and then close it caused the start of Ferrer's match against Juan Martin del Potro to be delayed by about 40 minutes. Ferrer needed less than two hours to beat del Potro 6-3, 6-2, 6-3.
Murray made the last eight for the fifth straight year by beating the 16th-seeded Marin Cilic 7-5, 6-2, 6-3, while Mayer ousted Richard Gasquet of France 6-3, 6-1, 3-6, 6-2. American qualifier Brian Baker's remarkable run ended with a 6-1, 7-6 (4), 6-3 loss to 27th-seeded Philipp Kohlschreiber of Germany.
"We stopped, obviously, a lot,'' Murray said.
"You're always a little bit edgy when you come out after a rain delay when you have the momentum with you. You stop, and then you come back out, and it feels a bit like you start from scratch again. I needed to serve well today and I got a lot of free points that helped me out.''
The 126th-ranked Baker was trying to become the third American qualifier to reach the quarter-finals at the All England Club. He was playing in Wimbledon's main draw for the first time after being off the tour for more than five years because of a series of operations, one on his right elbow. He was ranked 458th at the start of 2012 and will next week rise inside the top 100.
On Monday, top-ranked Novak Djokovic, Roger Federer and Mikhail Youzhny were the only men to complete their round of 16 matches.