PSG moved swiftly so sign the six-time Ballon d’or winner on a free transfer last month after it became apparent that Barcelona will no longer be able to afford his wages.
Messi is a four-time Champions League winner and joins a PSG side who have also added the likes of Sergio Ramos, Gianluigi Donnarumma, Georginio Wijnaldum and Achraf Hakimi to their ranks this summer.
With the likes of Neymar, Kylian Mbappe, Angel Di Maria and Marquinhos still at the club, this looks like the perfect season for PSG to end their Champions League hoodoo but Ronaldo thinks it is not a given for Mauricio Pochettino’s men.
The former Barcelona and Real Madrid striker never won the Champions League in his illustrious career despite playing in some star studded sides.
Speaking to AS, the Real Valladolid owner said: "It is still too early to say who will win the Champions League.
"Paris Saint Germain is in pole position, but there are many factors that influence the game.
"I played for Real Madrid for almost five seasons, in the Galacticos team [with the likes of Zidane, Beckham and Figo) and I never won the Champions League.
"Winning is never mathematical, even if you have the best on your team. It also applies to PSG."
