Ivanovic won the French Open last year after being runner-up in 2007
Ana Ivanovic has parted company with coach Craig Kardon after working with him for only four months.
Serbia's former world number one dropped out of the top 10 this week, following her fourth round exit from the French Open last month.
"I'd like to thank Craig for all his hard work, he's a great guy and I enjoyed working with him," said Ivanovic, now ranked 13th in the world.
Kardon is a former coach of Martina Navratilova and Lindsay Davenport.
Ivanovic, 21, last year won the French Open but has been unable to halt her slide down the world rankings.
Since last year's success at Roland Garros, she has since won just one event - the Linz Open last October.
The Serb has also been plagued by a persistent knee injury, resulting in her pulling out of the Madrid Open recently.
Her management company said she would be trained on a part-time basis by her sponsor's elite coaching staff during the grass court season including the Wimbledon championships which begin on 22 June.
The set-up includes Sven Groeneveld, who helped her during the 2008 season.