Johanna Konta has split with her coach Wim Fissette and the world number 10 will not play again this season due to a foot injury.
Konta has endured a poor run of form since losing to Venus Williams in the semi-finals at Wimbledon, winning only two matches in the six tournaments she has entered since that heart-breaking defeat in her home grand slam.
The 26-year-old was unlikely to qualify for the WTA Finals in Singapore even before announcing that she will not play in the Kremlin Cup this week.
Konta on Wednesday announced that she has parted with Fissett by mutual consent after just one season working with the Belgian and will not be back in action until next year as she sets about appointing a new coach less than a year after splitting with Esteban Carril.
The Brit said in a statement: "After careful thought and discussion, Wim Fissette and I have mutually decided to end our working relationship.
"Things ended very amicably and I wish Wim all the best. We've achieved a lot together and I want to thank him for all his patience, hard work and expertise.
"I will be working with my team over the coming weeks to find the right way forward for me and my tennis. The goal is to get a new coach or coaches in place as soon as possible but the focus will be on making the right decision rather than a quick decision."
Konta will not travel to Singapore to be a first reserve for the WTA Finals or play in the WTA Elite Trophy in Zhuhai.
She said: "Both are amazing events and I will really miss being part of them, but I want to make sure that I am fully fit to start preparations for what I hope will be an exciting 2018 season."