It’s the match the world has been waiting for. And it may well prove one that decides a Liga and, given the repercussions, goes a long way to settling to the Champions League.

Perhaps oddly, though, it isn’t quite the fixture that either of teams will have been waiting for. Up to about a month ago, it seemed as if both would swagger into it in a do-or-die clash as they decimated everyone else.

But, all of a sudden, they seem to be feeling the effects of what has been a relentless title race. For one, both have big worries about the Champions League after losing in midweek, and there is almost a sense that competition overshadows this game. Secondly, they’ve wobled in the league lately – particularly Real Madrid. While Barca have managed to win 11 in a row if still looking a little fatigued, Real have let six points slip in the last six weeks.

So, to a certain degree, far from shooting it out, this game might be about feeling each other out… not that we’ll be complaining. It will be enthralling either way.

Usually, the focus on the Messi-Ronaldo rivalry tends to be exaggerated in the build-up to these games. But not this time. One of the symptoms of the teams’ recent dips has been a complete over-dependence on the duo. Apart from their scoring records, both have been directly responsible for 31% of their teams’ points this year (as your commentator helpfully illustrates in the Examiner today *cough* *plug*). That is simply unprecedented in a top league. One difference remains between the two though: Messi has a much better record in Clasicos. He’s scored a series of key goals in them. Yes, although Ronaldo hit the winner in the Copa Del Rey, that was the least important game in last spring’s ‘world series’ of matches. It paled next to Messi’s Champions League deciders. He’ll need to step up today.

Along the same lines as the Messi-Ronaldo rivalry, it’s the Argentine’s team who have a clear superiority in Clasico head-to-heads. Mourinho seems to have a complex about Barca. That Copa Del Rey game remains the only Clasico he’s won since taking over.

Tonight, though, there is a difference: he doesn’t need to win. A draw will effectively secure the title. And that may change the dynamic. After this season’s Copa del Rey elimination, Mourinho said he was closer to the method he would use to finally defeat Barca in a big game. The only problem is that Real are nowhere near that kind of form now. But, also, do they need that method? There is an interesting psychological battle here akin to game theory as both sides may be subconsciously saving their best for any prospective Champions League final.

The teams:

Barcelona Valdés; Alves, Puyol, Mascherano, Adriano; Xavi, Busquets, Thiago; Iniesta, Messi, Tello

Real Madrid Casillas; Arbeloa, Ramos, Pepe, Coentrao; Khedira, Alonso; Di Maria, Ozil, Ronaldo; Benzema

Guardiola, not unsurprisingly, has been brave and potentially decisive. He’s dropped the misfiring Fabregas and Alexis (two goals in two months between them) and brought in youngsters Tello and Thiago. After a few games in which Barca only seemed to be able to go through Messi, it may be alternate their attack. Real, meanwhile, have an oddly offensive line-up given the fact they only really need a draw. Does Mourinho intend to press early on, as has occasionally proven successful.

Meanwhile, it seems Pique has definitively lost his place in the Barca starting line-up. Guardiola hasn’t been impressed with him this year. But he has proven adept at handling Ronaldo in the past.

And it’s off!

A fairly proactive start from both sides.

Ronaldo gets his head to a corner early on and, with Barca only having one player over six foot among their outfield players, it forces a fine save from Victor Valdes.

Real have started very positively. Barca taking a bit longer to get into their stride but that’s not unusual for them in big games.

Great chance for Barca as Dani Alves is on like lightning to thieve the ball from Sergio Ramos after a square pass from Pepe. Casillas is out very quickly though to block it down.

Peristent infringement from Munster at the breakdown grants Priestland an attempt on goal.

From 30 metres out, he draws a high, right-to-left effort inside the left post.

Scarlets 10-17 Munster

Real are making life difficult for Barca at the moment, interrupting their stride. Ramos just takes down Alves. That won’t be the first time that happens, as the Barca player does make the most of it.

This is really open at the moment. Both side really having a go. Benzema is onside there and drives a low, long strike at Valdes but the keeper holds it.

Tello does superbly to break into the box, beat his man and get a shot… but he’s offside. The Camp Nou cheers then groans as Alves’s subsequent shot inthe net is ruled out.

GOAL! Barcelona 0-1 Real Madrid

Barca’s lack of height at the back costs them! Pepe beats Tello to a header, Valdes can’t hold it, Puyol tries to block but Khedira essentially tackles it over the line.

That, incidentally, is the first time Real have taken the lead at Camp Nou since December 2007.

Messi almost manages to thread a ball through to Iniesta but Xabi Alonso does superbly to cut it out. There’s an aggression about Madrid that ensures their first to a lot of balls at the moment.

A better spell for Barca now as they finally settle and start to out moves together. More assertive. There’s still a bit of a spark missing about them though.

What a miss! Oh Xavi! That should have been a goal… but also should have been a corner. Messi threads Xavi through with a superb reverse ball but the midfielder shoots into the corner. It hits off Casillas and goes wide. Should have been 1-1.

Possession: Barca 71%, Real Madrid 29%

As ever, though, it’s the scoreline that matters.

Barca finally produce a move with Tello, Messi, Xavi and Alves linking up but Messi is offside when the right-back eventually rifles the ball across.

You have to say that, so far, this has been an absolutely vintage Mourinho display.

Pepe booked. Who had 44th minute??!

Half-time: the best 45 minutes of Mourinho’s managerial career so far? Quite possibly. Real have done everything right. Barca can’t seem to do anything right.

I’d imagine it would be utterly fascinating to be in either dressing-room at half-time during a game like this. Being honest, that is the kind of access we journalists can only ever dream about.

Real, however, have done everything right. Barca need to up their intensity and get fa few more bodies around that Real box – specifically actual finishers. The only problem is they don’t have many of them.

The second half is off. No changes either side.

Barca suddenly do look a bit sharper already in the second half. A bit more bite about them.

An interesting stat: under Guardiola, Barca have never gone two consecutive games without a goal.

Tello blazes over from the left after nice build-up from Barca. It’s looking like he’s going to have to be taken off. It was brave of Guardiola to start such a young man in this fixture.

Oh Tello! That’s a miss! Thiago picked him out with a brilliant pass, he was clean through, he actually could have taken a touch… and he sent it towards the corner flag. Should be 1-1.

Not much happening at the moment, which is an indictment of Barca. They’re still controlling the game… but there’s just no cutting edge about it. Guardila needs to change something. It’s amazing he hasn’t made a change with less than half an hour left.

Alexis Sanchez is about to come on… surely for Tello.

Xavi fires just wide from distance. A quarter of the game left. barca really needto up it now.

Alexis is on… but it’s not for Tello. It’s for Xavi.

GOAL! Barcelona 1-1 Real Madrid

Alexis has an immediate impact! Messi makes a great run to open up the space, feeding Iniesta. He flicks it on to Tello who again only forces a save from Casillas. But the ball pinballs around the box and Alexis forces it in.

GOAL! Barcelona 1-2 Real Madrid

Ronaldo arrives in a Clasico! Ozil plays a superb ball through and Ronaldo rounds Casillas before finishing superbly.

If Real win this – and even if they don’t – Ronaldo has banished the last criticism of his career really. That is a massive – and magnificently taken – goal, particularly when it came.

Fabregas comes on for Tello. Ten minutes left.

Mascherano drives powerfully over from distance. Perhaps a sign of how little Barca are creating. This is, as Wenger would say, “money time” and Barca don’t seem… motivated.

Ozil goes off. He’s put in some shift, including that super goal. it just doesn’t lok like it’s going to happen for Barca…

Four minutes of stoppage time… Barca need two goals.

Benzema strolls off with a minute and a half of stoppage time left. It’s surely time up for Barca… for the game and for the league campaign.

Ronaldo slides in and misses a sitter… but it looks like it won’t matter.

FULL-TIME Barcelona 1-2 Real Madrid

That’s it! Mourinho claims his first league win over Barcelona and real surely now claim their first league title for four years and 32nd title over all. It was vintage Mourinho and vindication for Ronaldo who scored a massive goal!