Prague - Former world No 1 Karolina Pliskova says she's parted with coach David Kotyza.
Pliskova hired Kotyza, the former coach of her fellow Czech compatriot Petra Kvitova, in December.
Pliskova has won three WTA tournaments with Kotyza.
She reached the semi-finals at the French Open and lost in the quarter-finals of the US Open to lose her No 1 ranking.
In a message to local media on Friday, the fourth-ranked Pliskova says she and the coach failed to agree on "the strategy of my further development."
It is not immediately clear who will replace Kotyza.