Messi and Ronaldo have been regarded as the two best players in the world for a decade now, but the added El Clasico element of the perennial rivalry ended this summer when the latter joined Juve after nine years with Real Madrid.
Messi admitted that he was "surprised" at the move and believes that Madrid will be weaker for losing his fellow five-time Ballon d'Or winner.
"Obviously [Madrid] are one of the best teams in the world, they have great players and squad but yes the departure of Cristiano from the squad makes them less strong," Messi is quoted as saying by Marca.
"It makes Juventus a clear favourite to win the Champions League due to the squad they had before and now with him on top. I was surprised by his decision, I did not think he would go from Madrid nor that he would go to Juventus. There were so many teams and I heard less about Juve but it is a very good team."
Ronaldo is yet to get off the mark in three competitive outings for Juventus, while Messi has four goals already this term.