Novak Djokovic is tough to beat at Wimbledon, indoors or out.
Playing the day's first Centre Court match on Friday under the retractable roof, defending champion Djokovic rallied past Radek Stepanek 4-6, 6-2, 6-2, 6-2.
When drizzle delayed the start of the third round, tournament officials decided Djokovic's match should be played inside.
An odd spectacle ensued: The roof closed as the sun came out and outside court covers came off.
"I was a little bit surprised, when I saw sunshine, that the roof is closed,'' Djokovic said.
"Obviously they're relying on a forecast that I don't think is very reliable here. But OK.''
The No. 1-ranked Djokovic missed opportunities to seize an early lead, failing to convert his first five break-point chances before he lost serve at love to drop the opening set. But he dominated from there, breaking in the first game in each of the final three sets.
"I was a set down but managed to make the crucial break in the opening game of the second set"
Also advancing to the second week was top-ranked Maria Sharapova. She rallied from a break down in the second set to beat Hsieh Su-wei 6-1, 6-4.
No. 3 Agnieszka Radwanska defeated Britain's Heather Watson 6-0, 6-2. Djokovic's fourth-round opponent will be 34th-ranked Viktor Troicki in an all-Serbian match. Troicki beat No. 15-seeded Juan Monaco 7-5, 7-5, 6-3, ending a record-equaling streak of seven straight five-set matches in Grand Slam tournaments for the Serb.
Fans were still buzzing about Rafael Nadal's second-round defeat, which ended under the roof on Thursday night, when Djokovic stepped onto the same court. His slow start briefly stirred speculation about another upset.
"I was a set down but managed to make the crucial break in the opening game of the second set,'' Djokovic said.
"And then I thought I played really well.''
Sharapova was still not at her best and the Russian will need to improve in the next round when she faces Germany's Sabine Lisicki, whom she beat in last year's semi-final. Lisicki knocked out up-and-coming American Sloane Stephens in three sets.
"The last two matches were tough," Sharapova, who has played three days in a row, told reporters.
"You have to improve with every match."
The half of the men's draw opposite Djokovic opened up when two-time champion Nadal lost to No. 100-ranked Lukas Rosol of the Czech Republic, 6-7 (9), 6-4, 6-4, 2-6, 6-4.
Nadal had reached the past five Grand Slam finals and won his seventh French Open title this month. He also had reached the final in his past five Wimbledons, winning the title in 2008 and 2010.
His departure creates an opportunity for three-time Wimbledon finalist Andy Roddick and Andy Murray, who seeks to become the tournament's first British champion since 1936. Both are on Nadal's side of the draw.