Maria Sharapova's first match since her return from injury has ended in defeat.
Sharapova has been struggling to find her best form
The number two seed was beaten in straight sets 7-6 (11-9) 6-2 by Belarus's Victoria Azarenka in round two of the Kremlin Cup in Moscow.
It was the first match in almost six weeks for the World number four, who has been nursing a shoulder injury.
She was not the only big name to fall. Amelie Mauresmo, seeded six, lost in three sets to Russia's Vera Zvonareva.
It was Sharapova's second successive defeat by an 18-year-old after she went out of the third round of the US Open in September to Poland's Agnieszka Radwanska.
Sharapova looked a shadow of the player who won two grand slam titles as a teenager. She made 45 unforced errors and served seven double faults in the match.
It also marked the third year in a row that the Florida-based Russian's stay in Moscow has ended in disappointment.
She was forced to pull out with a foot injury last year and was beaten in the quarter-finals in 2005.
Earlier, Zvonareva recorded her first win over Mauresmo when she came from behind to beat the sixth-seeded Frenchwoman 4-6 6-3 6-4 in the first round.
Zvonareva had lost her previous seven meetings with the former world number one.
"Finally I was able to beat her, it feels great," said the 24th-ranked Muscovite, who will now face Radwanska in round two.