Twelve months ago, Roger Federer amusingly ran foul of Australian Open security when he forgot to wear his tournament ID.
Now, his great rival and current men's world number one, Rafael Nadal, has been stopped by tournament staff inside Melbourne Park for the same reason.
Only hours before Nadal was to face Dominic Thiem in the quarter-finals, the 19-time major singles champion was walking through the bowels of Rod Laver Arena after finishing a practice session.
With a towel slung over his right shoulder, Nadal seemed to be casually going about his business as he made his way down a hallway and attempted to take a left turn through some doors until he was stopped by the security officer.
As is his duty, the security officer asked Nadal to show his accreditation, which — as it turned out — he was not wearing at the time.
Players, coaches, officials and others working at the Australian Open must wear or carry accreditation lanyards with identification details that are scanned at security checkpoints.
It is not certain whether Nadal went simply unrecognised, but it was not until the intervention of another security officer that he was given clearance and allowed to proceed.
Nadal appeared to be unfazed by what happened, as he patted the officer on the shoulder and went on his way.
He obviously learned his lesson, as the TV feed in the Melbourne Park media centre showed him wearing his accreditation lanyard around his neck not long before he entered Rod Laver Arena for his clash with Thiem.
Amazingly, Federer found himself in the same situation at Melbourne Park a year ago.
Despite being a six-time Australian Open champion and having 20 majors in his trophy cabinet, the Swiss was stopped by a security officer and asked to produce his accreditation.
Federer did not argue and waited until he was joined by members of his support team, who produced the necessary credentials. He was cleared to continue to his destination.
Rules are rules, as it is said, and it does not matter how famous you are.
