Phil Mickelson, longtime caddie Jim 'Bones' Mackay split

— -- Jim "Bones" Mackay was at Erin Hills early last week, scouting the U.S. Open venue even though he knew it was unlikely that Phil Mickelson, his longtime boss, would play in the tournament.

It turns out that scouting mission would be Mackay's last in a 25-year run with Mickelson during which Lefty would win 41 of his 42 PGA Tour events and all five major championships with Mackay carrying his bag.

The Hall of Fame golfer and veteran caddie announced their mutual split Tuesday with joint statements.

"Player-caddie relationships don't often last that long," Mackay said. "I will always be grateful that I was around to witness so much of Phil's career. When Phil hired me in 1992, I had one dream: to caddie in a Ryder Cup. Last year, at Hazeltine, Phil played in his 11th straight Ryder Cup. It was cool to have a front-row seat."

Tim Mickelson, Phil's younger brother, will take over caddie duties. Tim Mickelson, the former golf coach at Arizona State and now an agent for Jon Rahm, filled in for a day earlier this year at the WGC-Mexico Championship when Mackay became ill.

Phil Mickelson, who was unable to play at Erin Hills last week because of his daughter Amanda's high school graduation, began working with Mackay in 1992 just before the U.S. Open at Pebble Beach.

"After 25 very rewarding and memorable years, Bones and I have mutually decided to end our player-caddie relationship." Mickelson said. "Our decision is not based on a single incident. We just feel it's the right time for a change.

"Bones is one of the most knowledgeable and dedicated caddies in the world. 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. Amy and I, and our children, will always think of Bones, Jen, Oliver, and Emma as family.

We are looking forward to sharing life and friendship with them forever."

Mackay, 52, declined to comment beyond Tuesday's statement. He began working for former Masters champion Larry Mize in 1990. That was the year Fred Couples pegged him with his nickname, "Bones."

"He was trying to get my attention from across a room, and he didn't know my name," Mackay said in a 2010 interview. "Finally he just yelled, 'Bones.' And it stuck."

Two years later, Mackay was working for former U.S. Open champion Scott Simpson, who always told him to move on to a better player if an opportunity arose. That came with Mickelson, who was a three-time NCAA champion and U.S. Amateur champion while he was at Arizona State.

"The first time I ever caddied for him was at U.S. Open qualifying in Memphis, and he was an amateur," Mackay said. "I didn't really know him at all. We had a couple of five-minute conversations over the phone. And we didn't play a practice round. He had just won the NCAAs. He flew in and said, 'I'll see you on the tee.' And off we went.

"There were something like 80 guys for 16 spots. He shot 69 in the first round and broke the course record the second round. It was an amazing day for me. First, I couldn't believe how hard it was for me to clean a left-handed club. But it was incredible how talented he was. He shot 62, and then it was off to Pebble."

The only tournament victory Mackay missed came in 1991, before they knew each other. Mickelson won the Tucson Open as an amateur -- the last player to do so.

Other than a few overseas events, Mackay has been on Mickelson's bag for every round since that time, including Mickelson's most recent victory at the 2013 Open Championship at Muirfield.

"I wish Phil nothing but the best," Mackay said. "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."

Their relationship grew to the point that they had a running deal between them, where Bones was allowed to overrule one decision Mickelson made each year.

Mackay said in his statement that he'd like to pass it on to Tim Mickelson, "in all its glory."

Phil already vetoed the veto.

"Bones has not used his veto this year, and I heard a rumor that he is trying to pass his veto to Tim," Mickelson said. "For the record, vetoes are nontransferable."