Players had to pass Liverpool test before being considered for Manchester United
Manchester United's former chief European scout Martin Ferguson has revealed that during his big brother Sir Alex's time as manager players had to pass the Anfield test before they would consider signing them for the Old Trafford outfit.
The younger sibling travelled the world for United searching for stars who would enhance the team. Two key factors were always in his mind as he watched potential Red Devils.
He says: "The first thing I looked for in a player was ability. And the other big thing I looked for in a United player was, and I have to be honest about this, could he play at Anfield because our most difficult game is at Anfield.
"Everton and Chelsea away were difficult too but Liverpool at Anfield was the hardest so you had to see if a player had the ability and the attitude to do it there. I think it is the hardest ground to play at in England."
Even then, they had to be considerably better than what was already at the club. Daniel Alves, lauded for his performances at Barcelona, didn't arrive because Sir Alex was content with the right back he had at the time.
"I'd go and see good players and I'd come back and say to Alex about them, like the boy who was at Barcelona for years, Dani Alves," revealed Martin.
"I saw him play for Sevilla against Valencia and I really liked him so I said to Alex I had seen a really good right back and he said 'We don't need a right-back, we have Gary Neville.' I'd say about a midfielder and he would say 'we've got Paul Scholes'."
One of Martin's key recommendations who was given the nod, striker Ruud van Nistelrooy, proved to be a monumental success after moving to Old Trafford in 2001.
"I actually saw Ruud playing for a small club in Holland in a cup tie one night on a muddy pitch. I had gone to watch a goalkeeper (Sander) Westerveld who eventually signed for Liverpool. He was too soft for me but Van Nistelrooy was very impressive," stated Ferguson.
"He was playing against a centre-half twice his size who was kicking lumps out of him but he kept getting up, his touch was good, his movement was good and I thought I needed to go back and see him play again.
"Six weeks later Van Nistelrooy signed for PSV Eindhoven for £3 million. Then I watched him at PSV and I think we ended up paying £17 million for him. He was a natural and a selfish player, but good strikers are selfish.
"When I went to see him for PSV they had a lot of good players but I never took my eyes off Van Nistelrooy. He was great. I phoned Alex after the game and said 'Sign him. Don't hesitate' because I knew Arsene Wenger was interested in bringing him to Arsenal."
Ferguson, like his legendary brother, has more stories than JK Rowling.
Sticking with the world class player theme, he added: "I watched (Zinedine) Zidane when he was at Juventus and I found out the price and all the rest of it, but his wife was Spanish and wanted to go back to Spain and it never happened for us.
"You couldn't help but like Zidane (who moved from Juventus to Real Madrid and is now their manager). There were a lot of players that we liked but didn't sign and a big factor was the players we already had.
"I mean how could you better Paul Scholes? Scholes was as good as Iniesta and Xavi in my opinion. I will tell you now had Paul Scholes become available when he was at United the whole of Europe would have been falling over themselves to sign him. Even with Xavi and Iniesta, Barcelona would have signed Scholes without question.
"There were two players always mentioned to me when I went abroad to scout and they were Paul Scholes and Ryan Giggs. They were the two players in most demand abroad. Any club would have taken them."
Ferguson gave up scouting in 2013, though says it was not because his brother was stepping away from the manager's job at Old Trafford.
Speaking about his role, he says: "As a scout some clubs are good and some are poor with where they place you. Barcelona were great, they would always put you in the Directors Box.
"Real Madrid, I had to have a fight with them to get a decent seat. When (Jose) Mourinho was there he used to put me behind the dug-out so I couldn't see the pitch!
"People think it is an easy job, but it's hard work and you do a lot of flying and pick up germs and it started affecting my health. Eventually that's why I retired. Also I think it needed refreshing. I was getting older and my ideas weren't maybe like modern ideas but I loved the job and was glad to work for such a fabulous club."