Barcelona head to the Spanish capital on Saturday evening where they will go head to head with Atletico Madrid in a top of the table clash.

The sides are locked together on 49 points after a great first half to the season but both will be aware of the threat from Real Madrid who are just five points behind and no doubt hoping for a draw to allow them to narrow the gap at the halfway stage.

Atletico's start to this season may be a surprise to some but there has been signs that this was coming with improved league positions, two Europa League titles (2009/10 and 2011/12) and last year's Copa del Rey success, beating Real Madrid in the Final at the Bernabeu.  They have a built a strong, experienced squad with the majority of the first team regulars in the 26-30 age bracket and they have more than earned their place at the top of the table.

Atletico come into the game with a clean bill of health with Filipe Luis and Mario Suarez the only players listed as doubtful but both are expected to be available for selection.  The danger man is Brazilian/Spanish striker, Diego Costa who comes into the game with 19 goals and Barcelona will do well to stop him adding to that number.  Another player they will have to look is 22 year old midfielder, Koke.  Koke is an excellent player who has really come of age this season and has 4 goals and 8 assists.  He already has a host of clubs chasing his signature but he is playing regularly at a high level so it's unlikey he will be going anywhere in the near future.

Barcelona received a boost ahead of this game with the return of Lionel Messi in the midweek cup tie with Getafe.  He looked a little rusty at the start but by the end he looked to be getting back to speed, finishing with two late goals.  Barcelona manager, Tata Martino's biggest problem is where to fit the Argentinian into his starting eleven.  Cesc Fabregas has been in excellent form with four goals and two assists in his last three games and Pedro has four goals and three assists in the same period.  However, Alexis Sanchez will be expected to start alongside Messi and Neymar in Barcelona's attack so it is likely that Fabregas and Pedro will have to make do with a place on the bench.

Marc Bartra is likely to start at centre back alongside Gerard Pique as long as he has recovered sufficiently from the knock he picked up in last week's win over Elche.  The youngster has been having a great season and looks to have passed Carlos Puyol and Javier Mascherano in the pecking order.  

History tells us that Barcelona are favourites having won their last three league encounters at the Vicente Calderon but that statistic should be disregarded as the three games were not against an Atletico Madrid side who were good enough to be involved in a title race which the current side are.  A better indicator is the Spanish Super Cup were the sides drew twice in August.  Barcelona won the cup on away goals after a 1-1 draw in Madrid and a 0-0 draw in Barcelona.  The two games were extremely tight and provided the first signs that Atletico were a force to be reckoned with this season.  

Tomorrow's result won't decide the league title but it will have a bigger impact than a top of the table clash in other countries because of the Spanish leagues use of head to head records to seperate teams instead of goal difference.  A win tomorrow means that a defeat by a lower margin, a draw or another win in the return fixture in Barcelona is effectively worth an extra point to the victor.  

The game is huge for both sides but it is perhaps more important for Atletico Madrid as most of their squad have never been in a title race before and a defeat would perhaps affect their confidence more than Barcelona's.  Many will see Barcelona as favourites but Atletico have won thirteen home games in a row since drawing with Barcelona in the Super Cup and will undoubtedly give Barca the toughest game of their season.  Who will win is anyone's guess but you can be sure that when these two heavyweights collide the winners will have been pushed all the way to earn the three points.