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.