Colin Montgomerie has split with his caddie Alastair McLean after 10 years.
The Scot, seven times European number one, is expected to name a temporary replacement later in the day, said manager Guy Kinnings.
"It's a personal matter between the two of them and, even though they have enjoyed a highly successful relationship over the past 10 years, Colin feels a change is needed," Kinnings said. "But it's most certainly not a decision that's been taken lightly".
Montgomerie, who plays in this week's Benson and Hedges International Open starting at The Belfry on Thursday, will hold a news conference at the course tomorrow to explain his decision.
McLean, who began caddying for his compatriot in 1991, helped Montgomerie to the number one spot in the season-ending Europe money list every year from 1993 to 1999. The pair shared 31 tournament victories together and their final event was last week's French Open in Versailles, where Montgomerie tied for 23rd.
The 38-year-old Scot has not won anywhere in the world since last August's Scandinavian Masters and is determined to end his label as one of the best players not to have won a major championship.