During his second-round match, Jo-Wilfried Tsonga noticed a ball girl was fighting back tears after being struck by a ball.
The Frenchman stopped play to check on the girl before looping his arm through hers and escorting her off the court.
Twelve months on, Tsonga has revealed the girl, Guiliana, sent him a heartfelt message of thanks.
"Dear Mr Jo-Wilfried Tsonga," the letter reads.
"I wanted to take the opportunity to say thank you for helping me out on court during your round 2 match. I'm not sure if you remember me but I was the ball girl you escorted off court.
"I would also like to take the opportunity to apologise for the times when you asked for the ball but I did not service it to you or acknowledge you.
"I had picked up a virus which I was unaware of and it caused me to become dizzy and lightheaded. This also affected my vision and hearing.
"I apologise for not being able to perform my duties as a ball kid to the high standards that are expected.
"Thank you so much for the kindness that you showed me. I really appreciate that you were able to see that I needed some help and were kind enough to escort me off court."
The letter finishes by wishing Tsonga "all the best" for his remaining games, before signing off: "Giuliana, AO Ballkid no. 180."
Tsonga made the letter public in a tweet thanking Guiliana, which has been widely shared.
The world number 12 will play 2014 champion Stan Wawrinka in the quarter-finals after ending the run of Britain's Dan Evans on Sunday.