AUGUSTA, Georgia (REUTERS) - American Zach Johnson accidentally struck his ball during a practice swing on the 13th tee in the second round of the Masters on Friday (April 12), producing the kind of cringe-worthy moment every golfer dreads.

Johnson, giving his club a forceful swing through the air, clunked the ball into the marker, proving that even major champions can make silly mistakes.

"That's a first. I thought I had done it all but now I know I've done it all," Johnson said after his round.

Luckily, the 43-year-old emerged unscathed - pride not withstanding - as no penalty was applied and he went on to birdie the 13th hole.

"I was caught off guard," Johnson said.

"I actually hit a really good tee shot after that, so I think I recovered nicely."

Johnson ended his second round with a 73, a slight improvement over his day-one score of 74, as he aims for a repeat of his Masters-winning performance 12 years ago.

As for repeating his 13th-hole gaffe today?

"I don't think I could do it again if I even tried," Johnson said.