Sir Alex Ferguson
According to Alex Ferguson , he worked with just four world class players as Manchester United manager.
The Scot, whose new book 'Leading' was published today, guided the club to 13 Premier League and two Champions League titles during his 26 years at Old Trafford.
However for all those successful teams, Ferguson claims Cristiano Ronaldo, Eric Cantona, Ryan Giggs and Paul Scholes were the standout stars.
"They made the difference and the evidence is there," he told the BBC's Football Focus.
While the legendary boss brought in Ronaldo and Cantona, Giggs and Scholes rose through the club's academy and he believes no one can match what they achieved in the Premier League.
"The younger breed like Ryan and Scholes were just fantastic players and the thing about those two was longevity.
"Are there players who have played right through the whole of the Premier League and performed at the level they have? There are none, absolutely none.
"Of course Ronaldo was just a complete genius of a player."