Colin Montgomerie has split with caddie Alastair McLean just days before the US Open, the season's second major, at Oakmont in Pennsylvania.
Montgomerie and McLean reunited in 2004 after a two-year split
The Scot made the decision after missing the cut in the Austrian Open. The pair worked together for 10 years before reuniting in 2004 after a split.
"They've agreed to take a break, they needed to refresh things," said Montgomerie's manager, Guy Kinnings.
"Monty will probably hire a local this week who knows the course."
Montgomerie, who lost an 18-hole play-off to Ernie Els in the US Open at Oakmont in 1994, last won in December 2005 in Hong Kong and has slipped to 39th in the world.
And the eight-time European number one admitted "something had to change" after a third-round 72, three over par, sent him crashing out of contention in last week's Wales Open.
A closing 63 at Celtic Manor seemed to revive his spirits, though, and he declared: "I am getting my game back.
"There is no question that the dark, dark days of this year are over and I'm getting back to putting scores together as opposed to thinking about it."
Montgomerie will play with American Chris DiMarco and South African Tim Clark for the first two rounds of the US Open which begins on 14 June.