In Tennis, former world number one Ana Ivanovic has announced her retirement. The Serb made the announcement on Facebook last night. After her early exit from this year's US Open, Ivanovic had said, she would be ending her season early to fully recover from a series of injuries that have hindered her in recent years. She had said at that time that she will return to the sport. But, the 29-year-old Serb has now decided to bring her career to a close.Ivanovic had held the top spot for 12 weeks in 2008, the season when she claimed her sole Grand Slam by winning the French Open.