Borrowing a Playing Partner's Club Mid-Round Breaks Rule 4.1b

A golfer who leaves a club behind on an earlier hole and makes a hole-in-one by borrowing a partner's club has broken the Rules of Golf, regardless of how the shot turns out.

Can you borrow a club from another player mid-round?

No. Under Rule 4.1b, a player who starts a round with fewer than 14 clubs may add clubs during the round up to that limit, and a player may replace a club that breaks during play — but neither exception allows borrowing a club from anyone else playing the course, whether or not they're in the same group. Doing so is treated the same as carrying too many clubs.

In match play, that breach adjusts the state of the match rather than producing a stroke penalty. In four-ball play specifically, Rule 23.9 applies the penalty to the whole side, not just the player who used the borrowed club.

Can opponents overlook the breach?

Yes. Match play allows opponents to waive a breach if they choose to, which is why a golfer who borrows a club to make an ace can still have the hole stand — if the other side lets it. The rule doesn't forgive the breach; it simply gives opponents the discretion not to enforce it.

What about a self-called penalty for teeing outside the markers?

A separate scenario falls under Rule 6.1b, which governs playing from outside the teeing area. In match play, the opponent chooses whether to cancel the stroke, so a hole-in-one from outside the tee markers can stand if the opponent declines to cancel it. In stroke play, a player who calls the penalty on themselves takes two penalty strokes and must replay from within the teeing area — the shot that went in the hole doesn't count. Failing to correct the mistake results in disqualification.