Wolves striker Fabio Silva says it's difficult for young forwards coming through in Portugal.
Currently on-loan with PSV Eindhoven, Silva was likened to Cristiano Ronaldo when with Porto.
He said, "For me, Cristiano Ronaldo is the best player in the history of football. (Lionel) Messi is also fantastic, but Cristiano is special. There will never be another player like him.
"People have always criticised him and he has always proved them wrong. his mentality is impressive.
"It's not fair to compare young players to Cristiano Ronaldo. It's not even fair for him. His numbers, the records, the awards he's won... it's unparalleled. That's why I'm calm. People even criticise the best player in always, so I don't mind being criticised. Sometimes football is crazy."