Nigel Sears has resigned as head coach of women's tennis for the Lawn Tennis Association to coach former world No 1 Ana Ivanovic.
Sears, who spent four-and-a-half years in the post, said: "It's been a real privilege to be in charge of women's tennis at the LTA, and an honour to captain Great Britain's Fed Cup team, and I feel we've made considerable progress in the women's game over this period.
"I've been fortunate to work with some great coaches, trainers and physios, and I look forward to following the progress of our players over the next few years."
During Sears' time as head coach of women's tennis, five British women broke into the world's top 100, two made the top 50 and two girls (Laura Robson and Heather Watson) won junior grand slam titles.
LTA chief executive Roger Draper added: "I would like to thank Nigel for his significant contribution to the LTA over the past four and a half years.
"Nigel has been instrumental in developing the player programmes for our most talented girls and women, and he leaves behind a real sense of confidence and optimism that we can look forward to a bright long-term future in the international game."
British No 3 Anne Keothavong admitted her disappointment at Sears' departure.
She said on Twitter: "Really sad Nigel Sears has decided to resign from his position as Head Coach of Women's Tennis.
"He has been one of the most influential people in my career and it's been a privilege to work with him. It's a loss for British Tennis and I wish him all the best working with Ana."