Some might suggest that it was Sir Alex Ferguson who nurtured the talent of Cristiano Ronaldo while at Manchester United; others may declare that he was simply born to be great but it seems there is only one man to thank for helping the Portuguese forward become world class, and that is Jose Mourinho.
At least this is what Chelsea first team coach Steve Holland believes. He thinks that Mourinho was able to bring the best out of Ronaldo during his stay at the Bernebeu and it is hard to argue when you see his incredible goal scoring record at Madrid.
The former Manchester United midfielder has scored a staggering 208 goals in just 205 appearances since moving to Real Madrid for a then world record fee of £80m.
Ronaldo spent six years working under Ferguson at Manchester United and in his final two seasons at the club began to show his quality as he fired an impressive 68 goals in 104 appearances.
However, since that moment he has gone from strength to strength and Holland believes that is all to do with the influence of Mourinho.
"He (Mourinho) is always pushing, pushing the players to the maximum every day," Holland told Sky Sports. "That's evident not just in his teams, but in the individuals he's worked with.
"If you look Jose's three-year period working with Ronaldo, he's really evolved as an individual. He's not just a talented dribbler and runner with the ball who can score goals.
"He has become a top-level match-winner who wants to run in behind, make runs, threaten the goal. I don't think that just happens. That comes with pushing, even if it's the best."
In three years working under Mourinho, Ronaldo managed to score at least one goal a game across the entire season and he certainly seemed to thrive under the former Inter Milan manager.
Now Mourinho will have the chance to nurture an impressive array of attacking talent at Chelsea, with the likes of Eden Hazard, Oscar, Kevin de Bruyne and Andre Schurrle all looking to improve in their time at Stamford Bridge. But will any turn out as good as Ronaldo?