Every once in a while, Cristiano Ronaldo would drop a message to Portugal national team doctor Jose Carlos Noronha.

"Hey doc, any chance you could recommend a scientific article to read?" Ronaldo used to ask.

The Madeira-born superstar has already admitted "enjoying studying" and "being fascinated by the longevity field," so that didn't really come as a surprise to Noronha, who has known the forward since his first Manchester United spell.

The doctor, who is so highly rated back home that Jose Mourinho called him "The Very Special one", once described Ronaldo as "very inquisitive".