Four days after sparking controversy at the U.S. Open for putting a moving ball, Phil Mickelson issued an apology on Wednesday.
Mickelson was heavily criticised but initially remained somewhat unrepentant following a bizarre incident on the 13th hole at Shinnecock Hills on Saturday.
After hitting a putt that raced past the hole, the five-time major champion let his frustration get the better of him and struck the ball again while it was still rolling.
Although Mickelson incurred a two-shot penalty, resulting in him making a 10 on the hole, many argued he should have been disqualified for a deliberate breach of the rules.
The 48-year-old told reporters on Saturday that he "didn't mean to disrespect anybody", but has now acknowledged an error in judgement.
In a text to several golf journalists, reported by Golf.com, Mickelson wrote: "I know this should've come sooner, but it's taken me a few days to calm down.
"My anger and frustration got the best of me last weekend. I'm embarrassed and disappointed by my actions. It was clearly not my finest moment and I'm sorry."
Mickelson had offered to withdraw from the tournament after the incident, but USGA CEO Mike Davis assured him a two-shot penalty was the appropriate punishment.
The veteran left-hander duly closed with a 69 to finish in a tie for 48th.
