Navratilova, who won 18 Grand Slam titles as a player, was hired on a part-time basis in December and said that she had under-estimated the time it would take to make this proper and good, the BBC reported.
Radwanska stated on Twitter that they both agreed that as Martina could not commit 100 percent to the project then it was not going to work.
Radwanska, who is still searching for her first grand slam title, was beaten in the first round of the Stuttgart Grand Prix this week by Sara Errani of Italy.
Image: Agnieszka Radwanska of Poland reacts to a point in her match against Caroline Garcia of France at the WTA Dubai Open
Photo: Francois Nel/Getty Images