In viral live TV footage, Majchrzak could be seen taking off his Asics-branded hat and handing it to a young fan.
Too busy giving out autographs to other kids, the athlete didn’t realise that a much older US Open attendee had made a grab for the cap too.
A man seemingly snatched the worn headgear away from the kid and refused to hand it over, despite the boy’s audible protests.
The shocking video has made its way across the internet, with many slamming the presumed ‘thief’ as a ‘bully’
One X user lamented that the man had committed a ‘disgusting’ act at the tennis Grand Slam, questioning how anybody could take a present away from a kid in that manner.
Another typed: “Shame on this guy.”
“Maturity doesn’t come with age, but the acts,” complained someone else.
Majchrzak, who is gearing up to take on qualifier Leandro Riedi today (August 30) for a spot in the Round of 16, has taken to Instagram to give a major update on the situation.
“After the match I didn’t get to record that my cap didn’t get to the boy,” he wrote.
“Thanks to @asicstennis I’ve got enough caps so I’m prepared for that.”
Sharing four images of the child, the icon continued: “Hey Guys, could you help me find the Kid from my match @usopen @eurosportpl.
“If it’s you (or your parents see this), please send me a DM.”
Hours later, Majchrzak returned to social media to give fans the good news – the boy had finally been located.
“I am impressed by the power of the Internet,” he gushed. “We got it! All good now,” followed by a salute and thumbs up emoji.
Fans who have closely followed the US Open saga have been having their say, with one claiming: “Kamil Majchrzak won the hearts of fans around the world when he asked on Instagram for contact with the robbed boy to compensate him for his loss.
Someone else branded him a ‘legend’ while a third typed that the competitor was a ‘class act.’
“Credit to the Kamil for not noting why the kid didn’t get the cap. Which I totally would have mentioned because sometimes pettiness is required,” joked another fan.
A fifth commented: “What a class gesture absolute brilliance you need people like this in the world.”
Now that the matter is settled, Majchrzak can concentrate on his third round Men’s Singles match, set to take place on Court 5 today (August 30).
If the Pole beats Riedi, 23, he’ll enter round four, which would mark his best-ever result at the Grand Slam.