World number two Karolina Pliskova has confirmed she has split from her coach Conchita Martinez.
Former Wimbledon champion Martinez, who was second in the world herself during her playing career, started working with Pliskova on a full-time basis 10 months ago.
The Czech won four WTA titles in 2019 - the joint-most on the tour - but failed to make it beyond the fourth round of a grand slam after reaching the Australian Open semi-finals in January.
Last week, Pliskova was beaten in the last four of the season-ending WTA Finals by Ashleigh Barty.
"I decided I will no longer work with Conchita," Pliskova wrote on her social media accounts.
"It was tough decision, as the season was great. Thank you for all this year, and wish you only the best. Life is a change!"
Martinez, who coached Garbine Muguruza when she won Wimbledon in 2017, also posted a message on social media.
"Just a little note to inform you that Karolina and I have decided to take different paths next year," she said.
"It has been an incredible year full of great moments and emotions. I wish Kaja and her team the best for the future."