Lydia Ko has split with instructor David Leadbetter after three years.
Leadbetter confirmed Wednesday that he is no longer working with the top-ranked Ko. The 19-old Ko hasn't commented on the decision.
"These things happen in the world of coaching, whether it's Jurgen Klinsmann with the U.S. National Soccer Team or Novak Djokovic, who just separated from his coach Boris Becker this week," Leadbetter said in a statement. "This turnover is all part of the coaching business."
Ko turned to Leadbetter when she shifted her base from New Zealand to the United States. Before that, she had worked with Guy Wilson since taking up golf as a 5-year-old. Ko won four LPGA Tour titles this season and has 14 career victories.
"We wish Lydia the very best for the future and know that, going forward, if she is able to withstand the many outside pressures associated with being No. 1 in the world and, if her team keep their expectations realistic, then she can go on to even bigger and better things," Leadbetter said.
Ko also made a late-season caddie change, firing Jason Hamilton. He quickly landed with rival player Ha Na Jang.