Laura Robson has been criticised by her former coach Zeljko Krajan who believes the British number one lacks maturity and commitment.
The 19-year-old hired the Croatian after the London Olympics and it appeared as though the partnership would flourish as Robson made it through to the fourth round of the US Open, defeating Li Na and Kim Clijsters along the way.
However, Krajan, who led Dinara Safina to world number one, parted company with Robson prior to the start of the Madrid Open after a reported clash of styles between the somewhat laid back Brit and the hard taskmaster.
"The mentality is different. I did expect more from Laura but when it doesn't go that way any more it is not the time to stay," Krajan told The Times.
"She was not mature enough to do this kind of work enough times for me. She needed to be more serious and to commit herself more. She had to do this every day, not only in the big tournaments."
While Robson did make the third round of the Australian Open she has been knocked out in the first round of a tournament on six occasions this year and played poorly as Great Britain failed to reach the Fed Cup World Group.
There have still been moments to savour though as Robson secured her first win over a top-five player on Monday when she beat Agnieszka Radwanska but she was then beaten by Ana Ivanovic in the third round in the Spanish Capital on Wednesday.
The former world number one was forced to come from a set behind as she eventually overcame Robson 5-7 6-2 7-6 (7-5) to qualify for the quarter-finals in Spain.
Despite the defeat Robson, who is now ranked 41 in the world, will take confidence from her performance on the clay as she looks to put in a good showing at the French Open, a tournament where she has never advanced beyond the first round.