MELBOURNE, Australia - One day after the heavy favorite Serena Williams lost to Ana Ivanovic, another multiple Grand Slam champion crashed out in the fourth round at the Australian Open. On Monday, Maria Sharapova, a four-time Grand Slam champion and the No. 3 seed, lost to No. 20 Dominika Cibulkova, 3-6, 6-4, 6-1. Cibulkova, of Slovakia, has never been ranked in the top 10, but her victory meant that she has now reached the quarterfinals at all four Grand Slam events. Though she lost the third set fairly easily, Sharapova had given herself a good chance to win the second after falling behind, 0-5, eventually digging back to 4-5 before missing several crucial returns of second serves that allowed Cibulkova to serve out the set on her third try. Cibulkova said she did not see that Sharapova was visibly affected by the injury, and added that she thought Sharapova was trying to disrupt her momentum throughout the match. Sharapova, who had to battle in extreme heat for three and a half hours last Thursday to beat Karin Knapp, 3-6, 6-4, 10-8 in their second-round match, said her ability to escape with less than her best tennis had run out. Sharapova had been forced to miss the United States Open with a shoulder injury, and had only been able to play one tournament between August and the Australian Open. 11 Simona Halep. The Romanian won a marathon game at the start of the third set and eventually ran away with a 6-4, 2-6, 6-0 victory over No. 8 Jelena Jankovic of Serbia to reach her first Grand Slam quarterfinal. Halep, who began 2013 ranked 47th, won six titles last year, second only to the 11 won by Serena Williams. Later on Monday afternoon, in a rematch of last year's controversy-tinged semifinal, Victoria Azarenka was rarely threatened by Sloane Stephens, beating the last American left in the tournament, 6-3, 6-2. Azarenka dominated the match from the start while Stephens struggled with consistency, and too often was not proactive enough to dictate rallies with her superior power. While both players struck 20 winners in the match, Stephens had 32 winners to 20 by Azarenka, a Belarussian. Stephens, who was defending a large number of ranking points she gained from reaching the semifinals last year, will slip from 13th to somewhere around 17th. While not as eyebrow-raising as the finish to last year's match, which was marred by Azarenka taking a lengthy medical timeout after her lead in the second set began to slip away, there was little love lost between the two. Late in the first set, Azarenka pulled Stephens in toward the net with a drop shot, and Stephens landed a hard backhand passing shot between Azarenka's legs. Three points later, after hitting another drop shot that pulled Stephens forward, Azarenka responded with a head-high reflex volley that narrowly missed Stephens, leaving the American smiling broadly as she mimed applause with her racket. Stephens, who said she had "never hit anyone in a match," denied intentionally aiming for her opponent. "I thought she was going to move and she didn't," Stephens said. I don't know what was happening, but didn't think that would ever happen. Azarenka also downplayed the moment. "Maybe she had an open court, but she chose that shot," she said of Stephens. I have no problem with that. Azarenka, the second seed and two-time defending champion, most likely emerges as the favorite to win the tournament once again with both Williams and Sharapova out of contention. "I don't consider myself just a favorite because I don't consider anybody as the favorite," Azarenka said. I just go out there and play my best, because anybody on any given day - we've seen that happen last couple days - can bring their best game. You have to stay alert. It doesn't matter the level that you're No. 2 or whatever. Everybody has proven that anybody can beat anybody. In the quarterfinals, Azarenka, will face Agnieszka Radwanska of Poland, who defeated Garbiñe Muguruza of Spain, 6-1, 6-3.