Melbourne, Australia (SportsNetwork.com) - Serena Williams quest for an 18th career singles Grand Slam title will have to wait a few more months. The world No. 1 will have to start a new winning streak too. Serbian Ana Ivanovic stunned Williams, 4-6, 6-3, 6-3 Sunday to reach the quarterfinals of the Australian Open. The 14th-seeded Ivanovic ended Williams 25-match winning streak and dealt the American a shocking fourth-round exit. Ivanovic, who was the runner-up in Melbourne in 2008 and was the French Open champion later that year, took advantage of 31 unforced errors from Williams. "Its not easy playing such a champion and Ive never beaten her before," Ivanovic said during an on-court postmatch interview. Before this match, Ivanovic had lost all four previous matchups against Williams. In fact, she hadnt taken a set against her, but that all changed at Rod Laver Arena. A five-time Australian Open champion, Williams lost for just the second time in 53 matches at the event when winning the first set. Her only previous defeat came last year in the quarterfinals to Sloane Stephens. Williams fought back from a break down to win the first set, but in the second Ivanovic broke for a 3-2 edge. She finally finished off the set on her third chance, a forehand winner. "I had some confidence coming into todays match," Ivanovic said. "I really did certain things extremely well, you know, and I kept her under pressure I felt throughout the whole match." The errors then started to pile up for Williams, as she lost the first three games of the final set. Williams held serve to get within 5-3 and saved one match point when Ivanovic sent a forehand into the net. The encounter finally ended when Williams sent a return long. "I wasnt the best, but it was all Anas day. I thought she played really well," said Williams, who fired 13 aces. "I made a tremendous amount of errors. Im just not used to missing those shots." Williams has been dealing with a back injury, which she termed as not "life threatening" but said she was unable to get additional days off due to the schedule of playing essentially every other day as a Grand Slam tournament requires. She even contemplated not taking the court Sunday due to the injury, but gave Ivanovic all the credit for winning. "I think its almost good I lost today because now I know what I have to work on," added Williams, who pulled out of the doubles competition with her sister, Venus before their first-round match. That was because Venus had a lower left leg injury. Ivanovic will face either 30th seeded Canadian Eugenie Bouchard or Australian Casey Dellacqua in the quarterfinals. Only three players have won 18 Grand Slam singles titles in the Open Era - Chris Evert (18), Martina Navratilova (18) and Steffi Graf (22). Serenas next chance at No. 18 will come at the French Open at the end of May. Fourth seed Li Na of China bested 22nd-seeded Russian Ekaterina Makarova, 6-2, 6-0 in 59 minutes. Li, who lost to Victoria Azarenka in last years finale in Melbourne, will face Italian Flavia Pennetta in the quarterfinals. The 28th-seeded Pennetta, who did not play the 2013 Australian Open due to a wrist injury. upended No. 9 seed Angelique Kerber of Germany, 6-1, 4-6, 7-5. This is Pennettas first quarterfinal appearance at the Aussie Open, but her second straight such showing in a Grand Slam tournament. Pennetta, who fired eight aces, was ousted by Azarenka at the 2013 US Open semifinals. Since 1999, only one German player has advanced to the Australian Open quarterfinals. That was Andrea Petkovic in 2011. Cheap Asics Running Shoes China Wholesale .com) - NFL owners have unanimously approved the sale of the Buffalo Bills. Asics Shoes Clearance .com) - Coming off a pair of tough losses last week, the Syracuse Orange will try to put an end to their first losing skid of the season when they pay a visit to the Maryland Terrapins at the Comcast Center on Monday night in Atlantic Coast Conference action. http://www.wholesaleasics.com/ . The win gives Canada its fifth title at the World Sledge Hockey Challenge. "Weve got to keep pushing," said Westlake, who led Canada with five goals in the tournament. "The second you let off the pedal, everyone catches up. Discount Asics Shoes . -- When Steve Blake checked in at the scorers table with 5:25 remaining in the third quarter, Stephen Curry shook his head and shouted across the court, asking Golden State Warriors coach Mark Jackson not to take him out. Clearance Asics Shoes . In the opener of the World Group first-round series, world No. 18 Kei Nishikori defeated Peter Polansky of Thornhill, Ont.Ahead of Michael van Gerwens eagerly awaited meeting with Phil Taylor in Rotterdam, we look back at their first ever match in the Premier League. Van Gerwen, the Premier League leader, and second-placed Taylor are only separated by leg difference as the competition makes its first trip to the Netherlands for the closing night of the regular campaign.Two of the sports most successful players have produced a number of thrilling encounters in recent years as they have battled for silverware. Taylor shared the oche with Van Gerwen for the first time in the Premier League on the opening night of the 2013 season in Belfast. Sky Live: PL Darts night 15 Michael van Gerwen will be have home support when he faces Phil Taylor in Rotterdam on Thursday But did The Power or Mighty Mike come out on top?Click on the video above to see highlights of Taylors first Premier League match against Van Gerwen.dddddddddddd Also See: Sky Live: PL Darts night 15 MVG too hot for Barney PL Darts talking points MVG keeps Gibraltar title ' ' '