For the third time in less than three months, there’s a huge player-caddie shake-up on the US PGA Tour. And this time, it involves a pair with a particularly close relationship.

Jason Day has replaced longtime caddie and father figure Colin Swatton ahead of this week’s BMW Championship. Day will have friend and former high school roommate Luke Reardon on the bag, a move first reported by Golf Channel’s George Savaricas.

However, Swatton will remain as Day’s coach, according to Ben Everill, the US-based Australian who writes for PGATour.com and is well-versed in all movements within the Day camp:

Reardon could wind up having a short trial run this season. With Day sitting 28th in the FedEx Cup standings, he needs a solid week at Conway Farms to remain in the top 30 and advance to next week’s Tour Championship.

A 12-year-old Day first met Swatton at the Kooralbyn International School on the Gold Coast shortly after the death of Day’s father. Swatton, the school’s golf coach at the time, took Day, now 29, under his wing, and the two have had a successful partnership since, highlighted by Day’s win at the 2015 US PGA Championship and his ascension to No.1 in the Official World Golf Ranking.

“I lose my dad at 12 and then meet Colin, and to have him walk the journey with me, have him walk up the 18th hole with me, was just a special, special experience I could never forget,” Day said after winning the 2015 PGA at Whistling Straits. “It’s just – an amazing feeling I have.”

In June, an even longer player-caddie duo ended when Phil Mickelson and Jim “Bones” Mackay parted ways in June after 25 years together. Mickelson turned to his brother, Tim, as an interim replacement, while Bones, who will be inducted into the Caddie Hall of Fame this week, took a TV job with NBC/Golf Channel.

And about a month after that, Rory McIlroy fired J.P. Fitzgerald and replaced him – for now – with longtime friend Harry Diamond. So far, neither Mickelson nor McIlroy has experienced much success since making the change.

In all three cases, these were the only full-time caddies ever employed by the players since they turned pro.