REPEAT SOMETHING often enough and it becomes true. Well, sort of. Exhibit A: three English clubs are in the semi-finals of the Champions League. Surely, it must be because they have learned to play the continental' way.

Be organised defensively. Don't concede away from home. Don't take unnecessary risks. Pack the midfield. Remember that the ties last 180 minutes: after the first leg, it's still only just half-time.

Rafa Benitez' Liverpool play that way. Jose Mourinho's Chelsea did too, and now Avram Grant has maintained the same philosophy. And Manchester United, when playing in the Champions League, have embraced this approach as well. Surely that's the secret to the Premier League's success?

Maybe. Or maybe it's the fact that Premier League clubs have more money, better players and probably better managers than most. And that the competition has shot itself in the foot. Juventus and Bayern weren't in the Champions League. Milan's smoke and mirrors act had to fall apart at some point. Inter self-destruct too often to be taken seriously. Roma can't function without their best player. Real Madrid are held together with masking tape. Sevilla were rocked first by tragedy (Antonio Puerta's death) and then by their manager's walk-out (thank you, Juande). Lyon are led by Alain Perrin. And Barcelona, despite their final four place, are, frankly, a mess.

Whatever the case may be, anyone watching the Champions League semi-finals saw a very obvious common thread. Liverpool, Chelsea and Manchester United played the kind of cautious, ultra-defensive football which puts neutrals to sleep. The first two have been, of course, doing it for years. To be fair, there have been a few innovations. The way Benitez uses Dirk Kuyt and Ryan Babel - wingers in theory, but, in practice, high-energy runners whose main job is pressing high up the pitch - is creative and effective. Grant has persevered with Frank Lampard and Michael Ballack in the tight midfield three, something Mourinho was loath to do (and probably with good reason). That said, it's more of the same from those two.

But United's transformation is, frankly, surprising, not least because it amounts to a Jekyll and Hyde act. The United we see domestically, both in the league and the cups, is a free-flowing, attack-minded side, one which commits men forward, creates space out of nothing and then uses that space creatively.

In Europe, however, they happily take Wayne Rooney, supposedly their second most potent attacking force, and turn him into an auxiliary full-back. Paul Scholes, once a marauding midfielder, doesn't cross the halfway line. Carlos Tevez worries so much about tracking the opposition's deep-lying playmaker, that he nearly follows him into the dressing room.

You call this United?

And yet, there they are. A scoreless draw at the Camp Nou is not a bad result, particularly when one considers Cristiano Ronaldo's missed penalty. Sir Alex has plenty of domestic titles, it's the Champions League he really wants. Winning his second would separate him from the Matt Busbys, Jose Mourinhos, Fabio Capellos and Marcello Lippis of this world. Among active managers, only Carlo Ancelotti, Vicente del Bosque and Ottmar Hitzfeld have won it twice. Clearly, he has developed the idea of a two-speed United: all-out attack domestically, patient defending in Europe.

But does this approach actually work? Do you have to play that way to excel in Europe? A look at the last 10 Champions League winning sides might suggest otherwise. Real Madrid weren't like that in any of their three triumphs. Neither were AC Milan in their two. Nor, of course, did United take that approach in the Treble-winning season or Barcelona in 2005-06. In fact, you find just three sides who adopted that kind of conservative approach and lifted the silverware. Bayern Munich in 2000-01 (and it took penalties to do it), Benitez' Liverpool in 2004-05 (and they only did so after the most stunning comeback in the history of the game) and Mourinho's Porto in 2003-04.

There's another important difference. Certainly, in the case of Porto and Liverpool, they had little choice but to play that way. The former were, comparatively, a small side the latter were ravaged by the Houllier Era. Put another way, Sir Alex has Tevez, Ronaldo and Rooney. Liverpool had Milan Baros, Djibril Cisse and Luis Garcia. Porto had Derlei, Carlos Alberto and Benni McCarthy. Not quite the same thing, is it?

United has chosen this path. And it's a bold decision. Because switching tactical approaches so radically from game to game can have deleterious effects. Players aren't machines; what United are doing is extremely demanding from a tactical point of view. And there's an argument to be made that it's taking a toll on their performances, if not their results.

It's not just the fact that United have three draws in their last six games. It's the way they played. In the first leg against Roma - an opponent missing their best player, Francesco Totti - they defended so deep they were compressed in the final third for much of the game. Their two goals came against the run of play. Away to Middlesbrough, they took an early lead but failed to hang on, and had to come from behind to snatch a draw. When Roma - again without Totti - visited Old Trafford, United lived dangerously again, as De Rossi missed a penalty in the first half, before Tevez got the winner. Arsenal at home? Similar story. United were battered in the first half, Adebayor gave the Gunners the lead and then the home side scored twice to take the three points. And then came the Blackburn game: United again go a goal behind and chase the match for 67 minutes, until Tevez's unlikely winner.

Is this a direct result of the Jekyll-and-Hyde approach? Or is it just a long and grinding season taking its toll? Has Sir Alex added another dimension to his team? Or has he led them down a tactical cul-de-sac to the point where the players are neither fish nor fowl? We'll find out soon enough.