'They can target him as much as they like, Marc won't give them an inch,' a member of Crystal Palace's training ground team told Mail Sport over WhatsApp on Saturday.
'They' are Aleksandar Mitrovic and Dusan Vlahovic - Serbia's deadly, and rather physical, attacking duo.
'Marc' is Marc Guehi - the unassuming central defender thrust to the forefront of England's Euro 2024 tilt here in Germany.
Little is known of Guehi's talents here on the continent. That won't be the case much longer.
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Marc Guehi shone for England on the biggest night of his career as he started at Euro 2024
Little is known of Guehi's talents here on the continent, but that won't be the case for too long
The Crystal Palace defender delivered answers to all the questions fired at him with plenty left in reserve
'Marc will handle that battle, he's super intelligent. He's got the body strength to deal with those two, he won't get pinned by either. That's not a problem for him.'
And so it proved. On the biggest night of Guehi's career, the Palace defender emphatically delivered all the answers with plenty left in reserve.
As the cameras panned to Guehi in the tunnel before kick-off, his face was picture of tranquilly - as if he was meditating on a block of ice.
That's Guehi. Cool as cucumber. Here in Gelsenkirchen, the 23-year-old carried that serenity onto the pitch.
Never flustered. Never panicked. Just the air of a footballer who knew he belonged on this stage.
No inferiority complex, just a refreshing trust in his own ability.
Vlahovic, all 6ft 3ins of him, obviously fancied getting the better of Guehi here.
The attraction was clear: at an equal 6ft, Guehi was at a considerable height disadvantage.
Dusan Vlahovic (left), the Juventus forward, did battle with Guehi but lost the battle in Gelsenkirchen
Vlahovic smelt blood when it came to taking on the inexperienced Guehi but the defender preyed like a hawk
Vastly inexperienced at his level, too, Vlahovic smelt blood with Guehi and preyed like a hawk.
Unfortunately for the giant Serbian forward, he was barking up the wrong tree.
Mitrovic tried, too. But the former Fulham forward was dealt the same treatment.
On his major international tournament debut, Guehi demonstrated an overpowering conviction that suggests England have found the heir to Harry Maguire's throne as John Stone's central defensive partner.
His reading of situations here at the Veltins Arena resembled that of a seasoned international player - not one of a footballer making just his 12th England appearance.
The way in which Guehi nipped in front of Vlahovic, who'd just collected goalkeeper's Predrag Rajkovic's long pass, earned rapturous applause from England supporters. Guehi waited for his moment before pouncing.
Size and experience is inconsequential when you read the game like this. Front foot defending at it's best.
Indeed, what Guehi may lack physically he more than makes up with in intelligence and athleticism.
His progressive passing through the lines a feature of an excellent performance here.
There had been concerns over England's defence because of the absence of Harry Maguire due to injury
England's defence didn't look a step off the pace despite it being slightly patched together
In confirming Maguire's absence from this tournament due to injury, Gareth Southgate conceded: 'We will be different in defence, that's for sure.'
Different isn't necessarily a bad thing.
A quick scan of X, the social media forum formally known as Twitter, told its own story. One user simply posted 'Marc Guehi' next to a picture of a Rolls Royce.
There promising signs, too, of his developing partnership with Stones.
One attacks the ball, the other drops. It's simple stuff, but still needs execution.
They'll be better for this experience together, a relationship that can grow here in Germany.
Tougher tests are round the corner, that's the nature of tournament football. But Southgate will be encouraged by their opening.
Stones is one of Southgate's leaders. Here, there were signs Guehi will take over his mantle one day.
As England celebrated Jude Bellingham's opener, Guehi waved his arms frantically towards his team mates before pointing to his temples.
Later, as Serbia appeared to have England rattled, he urged his colleagues to rediscover the urgency in their passing that had their opponents chasing shadows for the first 20 minutes or so.
England faced plenty of second half pressure from Serbia, and Guehi stood up to be counted
On the back of an impressive season with Crystal Palace, Guehi came of age on Sunday night
And when the time came for him to to be strong and resilient in the face of Serbian second half pressure, Guehi did so unflinchingly.
'I think he's been great. Do you know what I've loved about his game? He's been so decisive, he's had decisions to make,' said former England goalkeeper Joe Hart on Guehi's display.
Literally everything he's done he's got right. He looks he looks great back there, he looks comfortable, he looks confident, exactly how I thought he'd play, because this team believes in him, and he's just showing everyone here what he's about.'
The night a quiet lad from Lewisham came of age.