Former French Open champion Ana Ivanovic announced her retirement from tennis at the age of 29 on Wednesday, saying she no longer feels fit enough to compete at the highest level.

Ivanovic became the first Serbian woman to win a Grand Slam tournament when she beat Russia's Dinara Safina in the 2008 French Open final, following in the footsteps of compatriot Novak Djokovic who won the Australian Open title the same year.

"There is no other way to say it. I have decided to retire from professional tennis. It has been a difficult decision but there is so much to celebrate," Belgrade-born Ivanovic said on Facebook.