Maria Sharapova crashes out of the Australian Open
Maria Sharapova followed Serena Williams out of the Australian Open after losing in the fourth round to Dominika Cibulkova.
Like world number one Williams, who struggled with back problems during her defeat by Ana Ivanovic on Sunday, Sharapova appeared hampered physically during her 3-6 6-4 6-1 defeat.
The third seed required off-court treatment after dropping the second set and there was no way back.
Cibulkova, seeded 20th, is through to her first Australian Open quarter-final and will play either Jelena Jankovic or Simona Halep next.
Sharapova had not had an easy time of it during the first three rounds, most notably a three-and-a-half-hour battle in extreme heat against Karin Knapp in round two.
She admitted after struggling past Alize Cornet in the third round that she still felt rusty following the shoulder problems that brought an early end to her 2013 season.
Initially things looked much better for the Russian on Monday as she broke the Cibulkova serve in the first game.
Her serve has been wobbly and she dropped it serving for the opening set but responded with another break of Cibulkova's to take it.
Slovakian Cibulkova had caused Sharapova problems in the past, winning two of their previous five meetings despite giving away nearly a foot in height.
And the 24-year-old was soon on the offensive in the second set, winning five games in a row as the Sharapova's unforced error count began to climb rapidly.
But one thing the Russian never lacks is fight, and instead of moving on to the decider, Sharapova battled, clawing back four games.
She could not complete the job, though, Cibulkova recovering from a double fault on her first set point to finally clinch it on her second.
Sharapova then called the trainer and left court, with the problem not immediately obvious, although she was clearly struggling with her movement.
Cibulkova took advantage with an immediate break of the Sharapova serve at the start of the deciding set and, although the third seed staved off break points in the third game, she was barely hanging on.
Cibulkova broke again to lead 4-1 and this time there was not even a hint of a comeback from Sharapova.
Meanwhile, Rafael Nadal progressed through to the quarter-finals of the Australian Open with a straight sets victory over Kei Nishikori, but it was a far from comfortable outing for the world number one.
Nadal had won all five of his previous meetings against Nishikori and, while he made it six out of six on Monday, he was pushed hard by his Japanese opponent before sealing a 7-6 (7/3) 7-5 7-6 (7/3) win at Rod Laver Arena.
The 13-time grand slam winner had not been broken previously in the tournament but dropped four of his service games before finally ending the impressive challenge of Nishikori in a match that lasted three hours and 17 minutes.
Next up for the Spaniard is Grigor Dimitrov, who became the first Bulgarian male to reach a grand slam quarter-final after beating Nadal's countryman Roberto Bautista Agut 6-3 3-6 6-2 6-4.
Nadal looked poised for a straightforward fourth-round outing as he broke Nishikori in the opening game following some loose shots from the world number 17.
The omens were not good for the underdog with Nadal's serve having proved infallible in his opening three matches in Melbourne, but the top seed was finally broken after four uncharacteristic errors in the fourth game.
Suddenly it was the 16th seed who was starting to look the more formidable and Nadal only just managed to hold in his next service game.
The set went with serve to a tiebreak, where Nadal showed his superior experience to emerge a 7/3 winner.
Nadal did not have it any easier in the second set either, and he was broken again in the fifth game after putting an overhead smash wide with the whole court to aim for.
That put Nishikori 3-2 in front but Nadal broke back in the eighth, taking the game with a crunching forehand down the line, and the 2009 champion produced a similar shot to take the set as he broke his opponent's serve again in the 12th.
Nishikori continued to fight in the third but his challenge finally looked to be fading as Nadal took a 4-1 lead after breaking in the fourth.
However, Nishikori still posed a major threat to the 2012 runner-up and, after failing to make the most of several opportunities in previous Nadal service games, he broke back in the seventh following the Spaniard's first double-fault of the match.
Incredibly, Nishikori also broke Nadal at his next opportunity to go 5-4 ahead and have the chance to serve for the set.
He could not capitalise though, wasting a great chance for a set point, and Nadal recovered to take that game and he then made no mistake in the tie-break to seal the match.