Prior to his arrival United were relatively inflexible. Our game had been, since 1990, 4-4-2: two quick, skilful wingers; a hard man and a dynamic box-to-box midfielder; a goal-scorer and a tricky genius up front. This endured for a long time but didn't serve us well in Europe: we couldn't resist the top teams well enough. In 1997, Ferguson began experimenting in the knockout stages in Europe. For example against Porto in 97 he played a 4-3-3: Beckham, Johnsen, and Giggs in a narrower midfield, with Cantona, Cole, and Solskjaer up front. We reverted to 4-4-2 for the semi-finals, and lost 1-0 home and away to Dortmund.

When Ferguson had signed Veron in 2001, he intended to use him in a four-man midfield with Scholes playing off the striker in Europe. This would close our usual counter-attacking game down and give us the ability to pack the midfield with tough players (Veron was a warrior in Italy) but also break quickly with precision passing and pace.

The trouble was that he had a mismatch on the flanks: Beckham was one-dimensional and starting to be found out, and Giggs was at the time slightly injury-prone but dynamic and drove us forward when fit.

Ferguson also struggled to coach at the top level in Europe, tactically. We really got lucky with '99, and in '08 we only beat Barca because of Carlos Q.

The best example of what Carlos brought was the semi-final vs. Barca in 2008. All the players and Ferguson talk about it extensively in their autobiographies. Queiroz studied Barca for weeks and watched the positions of all their players. He put specific markers on the pitch for all the players, showing them where they needed to stand when Barca were in possession. How they needed to react to certain players getting the ball. Very very detailed, methodical work.

He also helped United bring in more sports science, nutritional work, etc. Ferguson was one of the first managers to use an eye specialist to help improve peripheral vision in his playing staff, and he loved all the stuff Quieroz came up with.

Worth remembering that Quieroz was hated by the fans at the time!