Russell Henley was handed eight penalty strokes during Round 2 of the Mayakoba Golf Classic on Saturday for violating the PGA Tour's One Ball Rule, which states a player must use the same make and model of a golf ball for an entire round.
While switching balls in the middle of his second round, Henley mistakenly used one that was slightly different than his usual tournament ball. He didn't realize until after his round while signing autographs for fans and immediately brought it to the attention of tournament officials.
"It was a small dash, a different way it was marked that would have been easy to overlook," said PGA Tour rules official Brad Fabel, according to PGATour.com's Cameron Morfit. "He came to us and said he didn't know how it had gotten in his bag."
Henley believed he used the ball on Nos. 9 through 12 and received two penalty shots for each hole the ball was in play. Instead of shooting a 69 and making the cut, he signed for a 77 and will head home early.
The One Ball Rule isn't enforced by the United States Golf Association and falls under Rule 20.3 in the rule book. It's implemented for professionals and highly-ranked amateurs and the penalty for violating the rule is decided by the tournament committee.