Chelsea owner Roman Abramovich has changed the face of elite football around the world, former Blues sporting director Frank Arnesen has told BBC Sport.
Next month will mark ten years since Russian billionaire Abramovich bought the west London club for £140 million. Since then, the oligarch's huge personal investment has delivered the Champions League, the Europa League, three Premier League titles, four FA Cups and two League Cups to Stamford Bridge.
His reinvigoration of the club brought the likes of manager Jose Mourinho and star players like Didier Drogba to the Premier League, and Chelsea continue to be among the most powerful players on the transfer market as Mourinho returns for his second spell in charge.
Arnesen, who was poached from London rivals Tottenham Hotspur in 2005 and spent five years at the club, believes Abramovich's reign has become the model for all clubs wishing to become among the biggest in the game.
"I think he has been a pioneer, not only for football in England, but worldwide," Arnesen told BBC Sport.
"He was the first from outside who came in, bought a club and invested money.
"It had never happened anywhere in the world. Then you see Manchester City and many clubs with owners from outside, but he was the first who came in, was serious about it, made an impact and wants to do everything - not only for the first team but also the youth and the stadium."
Arnesen also spoke of how Abramovich takes a real interest in all aspects of the club, although he has to balance that with the commercial interests which allow him to bankroll Chelsea.
"Sometimes I spoke with him two or three times a week, sometimes you didn't speak with him for a month because he has a lot of other things - he has a big business to run - but when he was in London he'd just show up," Arnesen said.
"He'd call me and say 'who are you playing?' I'd say 'the Under-15s are playing Arsenal on Sunday at 3pm'.
"He would come with some guys, watch the game and enjoy it.
"He enjoys very much to go to the FA Youth Cup - he'd go the quarter-finals, the semi-finals and the finals. He was always there and would always congratulate us and the staff.
"He was very, very aware about those things and never forgot it. That is something people maybe don't know, but for me that showed he has a big heart for the club."