Has Ana Ivanovic lost some her magic that helped her win the French Open?

What has happened to Ana Ivanovic since she won her first and only grand slan-the french open in 2008? After that win she became the world #1 going into Wimbeldon and then lost early in the tournament.She was going to compete for Serbia in the 2008 Summer Olympics but sustained a injury and pulled out. since 2008, she has been on a rapid descent in the rankings going into the Aussie Open where she was ranked in the 20s and lost early once again this year.

Another former number 1 ranked player in the world who has lost a step is Maria Sharapova, who lost in the first round to fellow russian Maria Kirilenko (who lost to semi-finalist Zheng Jie of China).

Have these two players lost a step in their respective careers or have they each hit a downward spiral that which they might never recover from?