Phil Mickelson has announced he has ended his 25-year partnership with caddie Jim Mackay.
Mickelson, 47, won five majors and claimed 41 PGA Tour titles since teaming up with Mackay in 1992.
Phil's brother Tim will take over from Mackay, nicknamed 'Bones', and carry his bag for the rest of the PGA Tour campaign.
"Bones is one of the most knowledgeable and dedicated caddies in the world," Mickelson said in a statement published on the PGA Tour's website.
"He is always prepared and has the ability to make decisions in pressure-packed situations. Bones is without a doubt one of the most thoughtful people that I have ever known. The next player to work with him will obviously be very lucky.
"My relationship and history with Bones far exceeds golf. He has been one of the most important and special people in my life since the day we met, and I will always be grateful for everything he has done for me."
Not only did Mickelson win the Masters three times and both the Open and PGA Championship once, he also played in 11 consecutive Ryder Cups for the United States.
"When Phil hired me in 1992, I had one dream: to caddie in a Ryder Cup," Mackay said in a statement. "Last year, at Hazeltine, Phil played in his 11th straight Ryder Cup. It was so cool to have a front-row seat.
"I wish Phil nothing but the best. His game is still at an elite level, and when he wins in the future (definitely the Masters), I will be among the first to congratulate him."