"It is, without doubt, my last European Championship," the 39-year-old Ronaldo said after his tearful, emotionally charged performance in Portugal's penalty-shootout victory over Slovenia in the last 16.
That may have just confirmed what many were presuming anyway.
Still, there's now a definitive specter of finality to Ronaldo's long, headline-grabbing Euros adventure that could be brought to an end by Mbappé, the heir apparent to Ronaldo and Lionel Messi after their long-time dominance of the sport.
Mbappé grew up with pictures of Ronaldo on his bedroom wall.
A photo is inevitably doing the rounds on social media of what is apparently their first ever meeting, at Real Madrid's training ground at Valdebebas in 2012 when a 13-year-old Mbappé stood beside Ronaldo after a visit to the Spanish club where his sporting hero was the star player.
In 2020, Mbappé posted on Twitter, now X, that Ronaldo was his "idol."
And only a few months ago, Ronaldo reacted to Mbappé clinching a highly anticipated move to Madrid by writing on Instagram: "Excited to see you light up the Bernabeu."
That Mbappé can now end Ronaldo's European Championship career — who knows, it might even be his last ever major tournament — adds an intriguing subplot to a match that will be watched around the world.
"Let's go, let's go to war," Ronaldo said of the match against France, whom he considers as the top contender at Euro 2024 along with Spain.
He said he was driven to tears against Slovenia not at the prospect of elimination but because his main motivation these days is "making people happy" and he had a penalty saved in extra time.
"I'm moved by all that football means — by the enthusiasm I have for the game, the enthusiasm for seeing my supporters, my family, the affection people have for me.
"It's not about leaving the world of football. What else is there for me to do or win?"
Ronaldo heads into Friday's game having failed to score in eight straight matches at major tournaments — Portugal's last four at the 2022 World Cup and its four games at Euro 2024 — and with growing concerns about whether he deserves what appears to be a guaranteed spot in the team under Roberto Martinez.
Things haven't been straightforward for Mbappé, either, at Euro 2024.
He sustained a broken nose in France's group opener against Austria and has since been wearing a vision-limiting protective facemask during games. Mbappé has scored one goal and that was from the penalty spot against Poland - it's the only goal scored by a France player at these Euros.
"He will have to get used to it," France coach Didier Deschamps said of Mbappé and his mask, "because, to protect (his nose), he will have to wear it for a few weeks — or even a few months."
Few would have predicted the top scorer at the last World Cup (Mbappé) and the record scorer in men's international soccer (Ronaldo) to have just one goal between them heading into the quarterfinals.
But no one will be surprised if they come alive in Hamburg, with the pressure on and the occasion so big.
Mbappé, remember, scored a hat trick in the World Cup final and has been logging Ronaldo-esque scoring numbers in the first part of his career. He's already on 48 goals for France at the age of 25, and is also on 48 goals in the Champions League from 73 appearances.
He is chasing down Ronaldo's scoring records at both international (130) and Champions League (140) level and will likely only succeed by showing the same undimmed passion and desire as the player he used to copy as a kid.
As their countries' respective captains, they'll shake hands and embrace before kickoff. You can bet they'll do the same after the match.
By that time, one of them will be on his way home.
For Mbappé, there will surely be more European Championships down the road.
For Ronaldo, this could be the end of the road.