The mystery of Park Ji-sung has largely been resolved this season. Previously it was difficult to work out Sir Alex Ferguson's persistence with a player whose first touch was so unreliable it was often said his second touch was a sliding tackle, though he has gradually become Manchester United's go-to man in Europe.
Ferguson wants his players to perform in a slightly different way in the Champions League, with more emphasis on keeping possession and using the ball intelligently, and with more confidence the 30-year-old Park has come into his own. The player rather harshly left out of United's squad for the 2008 final in Moscow, after contributing fully to victories over Roma and Barcelona in the knockout rounds, is now one of the first names on European teamsheets.
"He's got the discipline, intelligence and football knowledge you need in the biggest games," Ferguson says. "Discipline is so much more important in the Champions League, and you need a slightly different type of discipline in Europe. Last season, for instance, one of the things that cost us was Rafael da Silva getting sent off in the return leg against Bayern Munich. There were other things but that was the killer for us. The boy was only 19 and he got carried away by the occasion. That can happen but there are some players you can normally rely on to keep a cool head and Park Ji-sung is one of them.
"When you pick teams for big games you need a core of discipline and he's one of the players who can give you that. And he's a fantastic professional. He moves and plays and moves again. That's the asset he's got. He doesn't watch what other players are doing with the ball, he gets himself into another position so he can be involved again. That's his value to us; he can be really important."
Park can also score goals – it was his winner against Chelsea that confirmed United's passage to a Champions League semi-final against Schalke – and in fairness the South Korean's all-round game has improved immeasurably in the six years he has been at United. The then 21-year-old announced himself with a splendid goal for his country against Portugal in the 2002 World Cup and, after impressing Guus Hiddink so much the manager took him back to PSV Eindhoven, a possible move to Chelsea fell through only because Manchester United made their interest known in 2005. Hiddink was clearly working on Roman Abramovich's behalf behind the scenes and Park was initially torn between a move to his dream club and respect for a coach he still describes as the biggest influence on his career.
"When I made up my mind for Manchester I felt I had betrayed Hiddink," Park says. "I knew he wanted me to go to Chelsea, so I found it difficult." If the story illustrates Park's ambition and strength of character, it also proves United were no slouches when it came to recognising talent and moving swiftly to make a capture. Not even Park's most ardent admirers would claim he was an instant success at Old Trafford but over the years he has proved well worth the modest outlay of £4m. "I wouldn't like to be without him," Ferguson says. "He is one of our most effective players and has been for a long time."
Park may need to be effective in Gelsenkirchen on Tuesday, since United's record against German clubs in the Champions League is not a glorious one. Apart from the win they left rather late against Bayern Munich in 1999, Ferguson's team have made European exits at the hands of Bayern, Borussia Dortmund and Bayer Leverkusen. "It's not a great record but there were different circumstances each time and on a couple of occasions we were unlucky," Ferguson says. "You can always expect German teams to be good professionals and to be competitive, but we've gathered plenty of experience too over the years. I've seen Schalke, they are a good side and obviously they have Raúl at the moment, so we will have to be aware of the threat in the final third."
Raúl apart, Ferguson can only be pleased with a semi-final draw that pits his side against the perceived underdogs of the final four and leaves Barcelona and Real Madrid to scrap it out so that only one Spanish giant can reach the final. "I don't want to sound complacent, we still need to get to the final ourselves, but I don't necessarily agree Barcelona are automatic favourites to win the other semi," he says. "Right from the time the draw was made I thought Real Madrid had a big chance. That 5-0 defeat in the league would have hurt them deeply, and the last couple of games have shown the gap between the sides is not really all that great. At a personal level I have no idea who is going to win out between Cristiano Ronaldo and Lionel Messi. They are both fantastic players yet quite different. My loyalty is with Ronaldo, though, as you might expect. He was an absolutely unbelievable player in the years he was at Manchester United."