Phil Mickelson changed balls mid-round. Did he break a rule?

Phil Mickelson, Tim Mickelson

Phil Mickelson and caddie — and brother — Tim Mickelson on Thursday on the 9th tee at Oak Hill Country Club.

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ROCHESTER, N.Y. — No, Phil Mickelson was not breaking the rules at the PGA Championship. 

But he would have been had he been playing on the PGA Tour. 

The sequence happened during Thursday’s first round at Oak Hill Country Club when an observer on Twitter — “Phil Mickelson Tracker” — noticed that Mickelson switched the model of his Callaway golf ball during play. The account tweeted: “Noticed Phil has changed balls mid round. Was using a Callaway that he lined himself with Sharpie, now using the official triple track ball.”

To which Mickelson responded, at 10:18 p.m.: “There is no one ball rule at the PGA.” He also added a smiling emoji. 

Notably, there is a one-ball rule on the PGA Tour, and they’ve penalized players because of it in the past. So why doesn’t the PGA Championship, run by the PGA of America? It’s actually simple. 

It’s their choice. 

The conversation here involves the rules for the golf ball — and model local rules. Let’s start with the former, which is actually what everyone follows. A USGA story explains things well when it writes:

“Generally, you will hole out with the same ball you play from the teeing area. You can always use a new ball when starting a hole. You can also substitute a different ball any time you are taking relief, including both free and penalty relief. Unless the one-ball local rule is in effect, the substituted ball could be any brand, make or model. On the putting green, however, when you mark and lift your ball, you must replace that same ball to finish out the hole.”

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In the PGA Championship’s case, “the one-ball local rule” is not in play. Let’s talk first about that rule. Another USGA story spells out Model Local Rule G-4 when it says:

“If this rule is in effect, you must play with the same brand, make and model of golf ball that you started the round with. This means that if you start playing with a Titleist Pro V1, you must play a Titleist Pro V1 for the remainder of the round and may not switch to another brand or even another model of Titleist golf ball.”

The penalties vary — if a player hits a shot with a different model of ball, they’re assessed a one-stroke penalty, or things could get worse. According to the rules, “when the player discovers he or she has played a ball in breach of this local rule, he or she must stop using that ball before playing from the next teeing area and complete the round with a ball of the same brand and model as used at the start of the round; otherwise the player is disqualified.”

But again, that’s up to the tournament. And that takes us to what model local rules are.

In short, they can be adopted. Or not. They advise. And the PGA of America is going with just the rule for the golf ball.  

“We basically play by the rules of golf, which allow you to change your ball in between holes,” Kerry Haigh, the chief championships officer of the PGA of America, told a reporter on Friday morning. “And now any time you substitute a ball during play, you’re allowed to.”

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On the PGA Tour, the one-ball rule has been enforced before, perhaps most memorably in 2019 at the Mayakoba Golf Classic. There, Russell Henley was slapped with a whopping eight penalty strokes after he discovered that he had used two different types of Titleist ProV1x golf balls during the second round. (In an act of sportsmanship, Henley turned himself in — after he discovered the mistake while signing autographs after the round.)

Notably, the PGA of America and the PGA Tour differ on the implementation of another model local rule. 

The rules of golf now allow for distance-measuring devices — i.e., range finders — and they’re in play at the PGA Championship. On Thursday, in fact, Mickelson’s caddie (and brother), Tim Mickelson, was seen using one. 

But model local rule G-5 lets tournament committees prohibit them. 

And the PGA Tour, along with the USGA, R&A and the Masters, enforce that at events.   

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Nick Piastowski

Nick Piastowski Editor

Nick Piastowski is a Senior Editor at and Golf Magazine. In his role, he is responsible for editing, writing and developing stories across the golf space. And when he’s not writing about ways to hit the golf ball farther and straighter, the Milwaukee native is probably playing the game, hitting the ball left, right and short, and drinking a cold beer to wash away his score. You can reach out to him about any of these topics — his stories, his game or his beers — at