Russell Henley went from being in contention for a fourth PGA Tour title to instantly packing his bags for a trip back home to Georgia - all because he used a different ball to the one he normally uses on holes 9 to 12 in his second round at the Mayakoba Golf Classic.
Henley, 30, was signing golf balls after his second round on Saturday when he realised that one of his balls was a slightly different model to the normal Titleist Pro V1x he regularly uses.
The three-time PGA Tour winner claimed he had no idea how this particular ball got into his bag, but that he had used it on holes 9 to 12. As a result of this, Henley was penalised two strokes on of these holes under a breach of Rule 20-3, turning his pars into double bogies.
Henley went from 7-under par after two rounds and what he thought was six strokes off the lead with two rounds to play, to missing the cut on 1-over par.
This particular rule comes into effect because the PGA Tour - and other high-level amateur events - adopts a One Ball Rule.
The USGA states: "When changing the balls, the player is permitted to substitute a ball of another brand or type unless the committee has adopted the One Ball Condition of Competition (see Apendix 1; Part C; Section 1c)."
"It was a small dash, a different way it was marked that would have been easy to overlook," PGA Tour rules official Brad Fabel told PGATour.com.
"He [Russell Henley] came to us and said he didn't know how it had gotten in his bag."
Here's more information on the rules violation...
According to reports, the breach of the rule took eight officials close to 90 minutes to discuss the incident before eventually deciding on the exact ruling and the appropriate penalty.
The final round of the Mayakoba Golf Classic went into a Monday finish as darkness prevented the end of play on Sunday evening.
Brendon Todd came out on top for the second week running on the PGA Tour with a narrow one-stroke victory.