Kyle Edmund has split from coach Fredrik Rosengren, who is retiring from the tour to spend more time with his family.
The British number one linked up with the hugely experienced Swede late in the 2016 season and, under the guidance of Rosengren, Edmund went on a stunning run to the semi-finals of the Australian Open last January.
He backed up that performance with a terrific 2018, climbing to a high of 14 in the world rankings after winning his first ATP Tour title in Antwerp last October.
Edmund said: “I am very thankful for the time we have spent together. As a team we have hit great heights, such as a top-15 ranking, a grand slam semi-final and a title in Antwerp in October, and I will be forever grateful.
“Fidde wants to spend more time at home with his family and I have the utmost respect for that. I would like to thank him for everything he has done for me and wish him all the best in the future.”
Edmund, 24, must now decide whether to seek a replacement or stick solely with his other coach, Englishman Mark Hilton, who joined the team at the same time as Rosengren.
It has been a frustrating start to the season for Edmund, who has been hampered by a knee injury and has not played since losing heavily to Tomas Berdych in the first round of the Australian Open more than a month ago.
He is due to return to action at the second-tier Challenger event in Indian Wells next week.