'I swear, I was with Jannik!': Sinner dials in with fan's mom in viral Rome video

WATCH: Jannik Sinner edged Alexander Shevchenko on Sunday night under the lights to reach the fourth round in Rome

We've heard of post-match autographs and selfies, but this was a first! Italy's top player Jannik Sinner had a good-natured response to being handed a cell phone by a fan on Sunday at the Internazionali BNL d'Italia: He chatted briefly with the man's mother.

The scene: Captured on video signing tennis balls, both big and small, and hats for fans of all ages, Sinner is soon approached off-screen by the fan, who's overheard saying, "Mama, there's a friend who wants to speak with you."

Realizing what he was about to get roped into, the affable Italian is spotted grinning before leaning in for a quick chat.

“Hi from Campo Centrale!” Sinner says in Italian, per the video's captions, signing off with a "Ciao, ciao," before returning the phone back into the stands and moving on.

"Mama, that was Jannik," the fan is then heard saying. "I swear, I was with Jannik!"

The top-ranked of three Italians through to the third round on the men's side at the ATP Masters 1000 event, Sinner is bidding for back-to-back quarterfinal berths in Rome. (Lorenzo Musetti and Lorenzo Sonego hope to join him in the last 16, but their third-round matches against Stefanos Tsitsipas and Frances Tiafoe were called off on Monday night due to rain.)

Eighth-seeded Sinner will be back on Campo Centrale on Tuesday when he faces No. 24 seed Francisco Cerundolo in the last 16.