British number one Laura Robson has split with her coach Miles Maclagan after just four months.
It is the second time in six months that the 19-year-old has changed coach after she parted company with Zeljko Krajan to work with Maclagan just prior to the grass-court season.
She reached the last 16 of Wimbledon and third round of the US Open under his guidance, but a run of just three wins in four tournaments has seen Robson decide that another changed was needed.
BBC tennis correspondent Russell Fuller said: "Robson informed Maclagan in a telephone conversation at the weekend that she wants to try a fresh approach in 2014: her enthusiasm to extend the relationship waned as she experienced a recent disappointing run of results in Asia.
"Croatia's Davis Cup captain Zejlko Krajan questioned Robson's work ethic when they parted company in the spring. Maclagan is a very different personality, so the 19-year-old must now consider very carefully who she does think can best harness her talent, and help improve her consistency away from the Grand Slams."
The world number 46 has previously been coached by Patrick Mouratoglou and Martijn Bok.