Polish tennis player Kamil Majchrzak has met a young fan after a video appearing to show a man snatching his hat from a boy in the crowd at the US Open went viral.

Majchrzak shared two clips on his official Instagram account in which he shook hands with two boys and presented them with gifts - including a cap similar to one handed to the boy and then swiftly taken off him in the clip.

"Today, after warm up, I had a nice meeting," the tennis pro wrote, adding: "Do you recognise [the cap]?"

The viral video, widely reported to be from Majchrzak's match on Thursday, showed the tennis player interacting with fans before offering a child the cap he had been wearing.

A man next to the child can then be seen taking the cap before the child had a chance to grab it himself. The boy can then be seen pleading to get it back.

Versions of the clip were subsequently shared on social media, with many users criticising the man - who multiple media outlets have since named as Piotr Szczerek, a Polish CEO of a paving company.

BBC News has approached Mr Szczerek through his company for comment.

Majchrzak also posted an image of him standing and smiling next to the boy wearing the cap.

"Hello World, together with Brock we wish you a great day!" the tennis player's caption said.

Majchrzak, 29, is ranked 76th in the world in men's singles.

He came back from two sets down to beat Russian ninth seed Karen Khachanov, also 29, in a second-round match at Flushing Meadows on Thursday, but was forced to retire injured during the first set of his third-round tie against Switzerland's Leandro Riedi on Saturday.

Majchrzak later confirmed he had torn an intercostal muscle.