* Nadal downed by 19-year-old Kyrgios
* Kerber ousts Sharapova
* Serena Williams retires sick
LONDON, July 1 (Reuters) - This time there was no escape for world No.1 Rafael Nadal.
For the fourth match in a row at this year's Wimbledon he got his fingers burned when losing the first set - only this time he was engulfed by player with dynamite in his strings.
How the tournament organisers must be slapping themselves on the back for handing Australian upstart Nick Kyrgios a wildcard.
On Tuesday the 19-year-old world number 144 took his dream Wimbledon debut to dizzy new heights with a spellbinding display on Centre Court to outplay the twice champion using a barrage of aces and crunching baseline winners.
His 7-6(5) 5-7 7-6(5) 6-3 win was the first by a player ranked outside the top 100 over a world No.1 at a grand slam since Jim Courier lost to Andrei Olhovsky in 1992.
Olhovsky never did much else but Kyrgios's victory, sealed with a 37th ace, felt as though it could be a seminal moment in the evolution of men's tennis - a warning shot to the "big-four".
Yes, Lukas Rosol and Steve Darcis, also ranked outside the world's top 100, ended Nadal's previous two Wimbledon campaigns, but they played probably the matches of their careers to do it.
Kyrgios's career is just beginning and the way he overwhelmed Nadal with a fearless brand of tennis, who knows where his first Wimbledon adventure could end up?
"He is acting to me like he can win the whole tournament," three-times Wimbledon champion John McEnroe said after witnessing a match that will enter Wimbledon folklore.
"The last guy that I saw like that was Boris Becker, a teenager who just believed that he would beat everything that was put in his way."
While magnanimous in defeat, Nadal offered a few words of caution.
"It's easier when you are arriving. Everything is new, nothing to lose. Everything is good. We'll see if he's able to improve and play at a very high level for a long period of time, but I wish him all the best."
Nadal won the French Open aged 19 and has gone on to capture 13 more grand slam titles.
Kyrgios described himself as "just a normal 19-year-old kid" on Tuesday but said some pre-match comments from his mother Norlaila that Nadal would be a match too far for her son had fired him up for the biggest day of his life.
"I was actually reading a comment that she thought Rafa was too good for me," he said. "It actually made me a bit angry.
"I'll just text her a smiley face!"
Kyrgios's exploits topped what had already been a dramatic eighth day of the championships including defeat for Maria Sharapova and the sight of distressed world No.1 Serena Williams serving a game of double faults in a third-round doubles match with sister Venus, before retiring with an illness.
Roger Federer's vintage Wimbledon continued, though, as he glided past Spain's Tommy Robredo 6-1 6-4 6-4 to reach the quarter-finals of the grasscourt slam for a 12th time.
The 32-year-old, yet to drop a set in four rounds, dazzled the Court One crowd with his artistry, making the game look ludicrously easy against the 22nd best player in the world.
"I feel physically in tip top shape," Federer, who now faces an all-Swiss quarter-final against Davis Cup team mate Stanislas Wawrinka, told reporters, although his mood may have been soured later as Switzerland lost to Argentina at the World Cup.
While Federer is facing an unusually busy schedule at Wimbledon because of weather interruptions, Wawrinka will be playing a third match in three days on Wednesday.
Australian Open champion Wawrinka beat Feliciano Lopez 7-6(5) 7-6(7) 6-3 without any major alarms although the match ended with the players in a heated argument at the net.
Big-serving Milos Raonic celebrated Canada Day by becoming the first man from his country to reach the quarter-finals at Wimbledon in the professional era, beating Japan's 10th seed Kei Nishikori 4-6 6-1 7-6(4) 6-3.
Wimbledon's second Tuesday is usually reserved for the women's quarter-finals, but with the schedulers playing catch-up after this year's rain delays, only two took place.
Czechs dominated the bottom half of the women's draw where Lucie Safarova's 6-3 6-1 defeat of Ekaterina Makarova set up a semi-final clash with compatriot and 2011 champion Petra Kvitova who defeated unseeded Barbora Zahlavova Strycova 6-1 7-5.
With a Czech finalist guaranteed, the top half of the draw took a further twist when Russian firebrand Sharapova, despite saving six match points, had her hopes of celebrating the 10th anniversary of her sole Wimbledon triumph with a sequel, rudely ended by dogged German Angelique Kerber.
The screaming fifth seed threw everything in her formidable arsenal Kerber's way, but after recovering from a wasteful opening set tiebreak to level, she went down 7-6(4) 4-6 6-4.
Though not the victory the French Open champion craved, she showed true champions' spirit to haul back a 5-2 deficit in a thrilling finale to a match she might have gone on to win had she taken a point to level at 5-5.
Instead, despite blowing a 0-40 advantage in the final nerve-jangling game Kerber sealed victory when Sharapova flailed a backhand over the baseline.
"I was a little bit nervous because I was thinking, you know, if it's now 5-5, everything starts from zero," Kerber, who faces 20-year-old rising star Eugenie Bouchard in the quarter-final on Wednesday, said.
A day after Bouchard became the first Canadian to reach a Wimbledon quarter-final in the professional era, compatriot Milos Raonic underlined the country's upward curve with a four-set victory over Japan's 10th seed Kei Nishikori.
Not a bad way to celebrate Canada Day, although Raonic will not be partying with Kyrgios to face on Wednesday.
Last year's runner-up Sabine Lisicki made sure there would be two Germans in the women's quarters when she overcame a shoulder injury to beat Kazakhstan's Yaroslava Shvedova 6-3 3-6 6-4.
She will face Romania's "Miss Consistency" Simona Halep after the third seed raced to a 6-3 6-0 win over Kazakhstan's Zarina Diyas. Halep reached the French Open final earlier this month and began the year with a quarter-final run in Australia. (Reporting by Martyn Herman; editing by Clare Lovell)