Inter Milan manager Simone Inzaghi was overheard warning Marcelo Brozovic about Harvey Elliott ahead of their game against Liverpool on Wednesday evening.
The incident happened in the tunnel at the San Siro, shortly before the Reds recorded a crucial 2-0 win thanks to goals from Roberto Firmino and Mohamed Salah.
Elliott, 18, may have been an unknown quantity to Inter and Inzaghi heading into Wednesday's fixture after a remarkable emergence at Anfield.
The England youth international was signed by Liverpool in July 2019 and, after just eight appearances in his debut campaign, spent last term on loan at Blackburn Rovers.
Elliott was given his chance by Jurgen Klopp at the beginning of this season - only to suffer a fracture dislocation of his ankle against Leeds in September.
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Many expected him to be out for most of the season but he made a stunning comeback within five months, coming on against Cardiff in the FA Cup on February 6.
After proving his fitness domestically, Klopp gave Elliott the nod for Liverpool's vital Champions League tie against Inter and he did a decent job in central midfield.
And Inzaghi was keen to warn Brozovic about Elliott just moments before kick-off.
"Keep an eye out, perhaps they put that lad in midfield to man-mark you," the Italian said, as reported by Mediaset Infinity (via Liverpool Echo ).
Elliott was replaced by Naby Keita just before the hour, when the game was goalless. Each team are permitted five substitutions in the Champions League this season.
The former Fulham youngster broke two records against Milan. At the age of 18 years and 318 days, he became the youngest Liverpool player to start a Champions League game.
The previous record holder was Trent Alexander-Arnold, who was 18 years and 354 days old when he started against Russian outfit Spartak Moscow in 2017.
Elliott has also become the youngest Englishman to make his Champions League debut in the knockout stages.
He's beaten Kieran Gibbs' record - and by some distance. The former Arsenal left-back was 19 years and 201 days old when he featured in the quarter-finals in 2009.
Discussing Elliott's performance, Klopp said: "It was absolutely OK, but Harvey can play much better, we know that.
"The reason Harvey played was because we knew which spaces we had to play and it's usually naturally his area, these half-spaces around the midfield three, being very flexible, naturally offensive-minded and all these kind of things. That's why he played.
"He had really good moments but we all know he can play much better. He did the job, he was working incredibly hard and all these kind of things.
"When you are 18 years old and play against one of the most experienced teams in world football and they are Italian on top of that, for an offensive player it's not a walk in the park.
"It was a very, very important game for him and very helpful for us as well."
