John Toshack, the former Real Madrid manager, insists Manchester United hold the upper hand ahead of their Champions League semi-final with Barcelona on Wednesday.

While Liverpool and Chelsea meet in one semi-final, United must revisit the Nou Camp — the scene of their famous triumph against Bayern Munich in 1999 — with Barcelona standing between Sir Alex Ferguson’s team and a place in the final in Moscow on May 21.

Toshack insists United are clear favourites for the tie whether Lionel Messi plays or not. The Argentina playmaker is a doubt ahead of the match, having made just two substitute appearances since returning from more than a month out with a hamstring injury.

Whichever Barcelona team takes the field Toshack feels the English champions hold the edge.

"Manchester United are favourites with or without Messi," Toshack said. "But if suddenly they lose a player like [Rio] Ferdinand or [Nemanja] Vidic and Messi is on the pitch, the tie could turn around 180 degrees."

He added: "Ferguson is the first person who would not want to go in as favourites, but what what happens is that if Rijkaard, [Rafael] Benitez or [Avram] Grant do not win the European Cup, then they could be out on the streets. Only Ferguson will continue whatever happens. What a demand! You have to win the the European Cup. And the Champions League is even more difficult than in my time. It is terrible to say that if you do not win the Champions League you have failed, but it is like that now."

The former Liverpool forward says he believes his old club will contest the final with United, although he admits he expects a few twists and turns along the way.

"Now I see it being Manchester United and Liverpool, but just the same it could be Barca-Chelsea. Injuries and suspensions could play a big part yet. The coaches must be aware of the influence that a goal conceded at home could have on the fans and on the players. When you reach this level, it is almost like a game of chess. You need to consider all the details."