For me to consider someone like Messi world class, he needs to leave his comfort zone. In Spain he's feared, and defenders are frightened to tackle him, much in the same way Henry was in his Arsenal days. I always feel with Messi a strong and focused defence can keep him quiet, and I'm hoping a fully fit Rio-Vidic with Fletcher in front defensive triangle will keep him out in May (we did it in 08, the midfield element was missing in 09 which really played to his strength of running at a defence).
The fact that defenders in Spain, and the weaker European teams, don't like to tackle him, plays to his strength of running. Take that chance away and he's quiet. He doesn't produce the special strikes a la Henry/Maradonna/Ronaldo the elder could. For me, he needs to take his game abroad, face a different mentality of defending and conquer that before he can be elevated up to the heights. Zidane, Maradonna, Ronaldo, Cruyff.... All excelled in world class teams, in different countries, hence why they deserve the adulation. Some players considered fantastic at the time tried at and failed, and thus wont be remembered worldwide, players like Owen spring to mind (he was the dogs at Liverpool). Also those mentioned before excelled on the World stage, even if they didn't all take home a World Cup.
Interestingly, no one mentions Raul in these discussions, and I think its for the reasons above, he never left his comfort zone and showed he's got what it takes to dominate whereever until it was far too late.... No one can doubt his quality and sucess, but still never gets a second glace as he's not done anything to spread his reputation (alas, call me blinkered, but Giggs fits into that category for me.... has the skill, but wont capture the imagination of the world)
In response to Ikki's nomination for Gerrard, I'm arguing against it, not because I think he's a bad player, but because
A) Whilst he has the talent, he's not consistent with it, and it's very noticable when its going to waste, his 'Hollywood ball' mickey-take isn't made up, its due to the amount he wastes trying to be flash when there isnt a need. Level that one against Zidane, Platini, Beckenbaur, Matthaius etc
B) Whilst he's been the kingpin in a team built around him, outside of his comfort zone he's not produced the way a world class player should (same argument used against Messi so far). In 10 years as an England regular, he's only sparingly offered glimpses of what he can do, and is regularly accused of being wasteful. I'll take his argument that he's not in his best position, and playing at the same time as Scholes and Lampard has meant he's been shunted about, but still, his performances at the top have raised too many questions too many times.
Saying all that, for the last 10 years he's been the one scouse **** i wouldn't mind in our team.