Upamecano has earned huge praise since Thursday’s victory and Cundy has joined the list of those raving about the 21-year-old.
And the pundit believes he would be a good signing for Chelsea, who are in the market for defenders this summer.
“Largely, you look at the two squads, they went into [the quarter-final] as second-favourites, especially losing Timo Werner as well,” Cundy said on talkSPORT.
“You’ve got some big names, some household names in football in the Atleti team but I have to say, the boy at the back, Upamecano, what a performance
I was looking at him thinking, as the game was developing, ‘this was the first time I’ve had a close look at your game’ and I was watching him and he was just immense.
“I was thinking: ‘Chelsea could do with him
He’s 21 years of age, it’s the best performance I’ve seen of a young centre-half in a very, very long time.”
Upamecano has spent the last three years at Leipzig and has made 112 appearances for the Bundesliga side.
He is yet to be capped by the senior France side but has played for the youth teams from under-16s up until under-21 level.
Former Chelsea player-manager Ruud Gullit instead thinks Manchester United should try to sign the defender.
Gullit claims that is the area of the pitch Ole Gunnar Solskjaer must improve first.
“He bought a good defence. He bought a goalkeeper and good defenders because everything starts there.
“And I think Man United should start there as well. And I think I saw something amazing with Leipzig and Dayot Upamecano.
“He was outstanding [against Atletico Madrid]. He can play football, he’s hard in the tackle. Defence is what I would start if I was Man Utd.”