They've navigated their way to the semi-final stage of the tournament without too many problems, but know they face a tricky tie against their fiercest rivals Real Madrid.

In the early part of the season Barca seemed to have the better of Jose Mourinho's side, but Real's win in Copa del Rey certainly indicates that the former Chelsea boss is in with a chance of overcoming the Catalan side, even if the Champions League betting doesn't make his side favourites.

Perhaps the biggest worry for Real is the fact that they will have to do the business in not one, but two games. As Arsenal proved earlier in the season it's perfectly possible to take a lead into the second leg of a Champions League tie, but holding on to it is a different matter entirely. No one will know this better than Mourinho after his Inter Milan side only just held on to a first leg lead at the semi final stage last season.

Barcelona's style of play is so efficient, and they keep the ball so well, it's almost impossible to get the better of them over two games as their opponents can barely afford to make a single mistake over the course of 180 minutes. Those looking to bet on Champions League winner should bear this in mind.

With this in mind, Mourinho will no doubt look to stifle the acting threat Barca have in spades. If he fails to do so, then whoever they meet in the final will have the best possible opportunity of stopping Barcelona's seemingly unstoppable charge towards Champions League glory.

As Arsenal showed earlier in the year anything can happen over the space of 90 minutes. Barcelona are very good, but they're not unbeatable.