( CNN ) -- Barcelona and Real Madrid lock horns Saturday in the first of four 'El Clasico ' showdowns in 18 days which will define their respective campaigns in Spain and the Champions League . Barcelona go into the La Liga match at the Santiago Bernabeu with an eight-point lead in the standings and with only seven games remaining . But the motivation for Jose Mourinho 's Real will be to disrupt their arch-rival 's serene progress to the Spanish title ahead of further matches in the final of the Copa del Rey and then the two-legged Champions League semifinal . Victory for Barca will complete a league double over Real , who they routed 5-0 earlier in the season in the Nou Camp , and all but wrap up the title . It was the heaviest defeat of Mourinho 's stellar managerial career and clearly still smarts as he refused to answer questions at his pre-match press conference Friday and offered up his assistant Aitor Karanka to the anger of journalists . `` Every time he talks , it 's blown out of context , '' Karanka told the reporters , who exited in droves when it became clear Mourinho had snubbed them and would not answer their questions . `` He prefers being relaxed and calm and it is n't the first time that I 've given the press conference . It 's just our way of working , '' added Karanka . But Madrid 's record signing Cristiano Ronaldo , who has scored 28 league goals this season , believes they can reverse the result in their home stadium . `` It is completely different to the first game ( when Real lost 5-0 ) , '' Ronaldo told AFP . `` We have to think it is possible ( to win ) because they ( Barcelona ) are not from another planet . `` They are one of the best footballing sides but we are in good shape and have to be confident that the best team will win . '' Barcelona have won the last five El Clasicos , scoring 16 goals against just two , but coach Pep Guardiola is taking nothing for granted . `` We wo n't make the mistake of going to the Bernabeu thinking nothing is lost if we lose , '' he said Guardiola . `` We have the opportunity to take a decisive step towards the league title . '' Guardiola has defensive problems with captain Carles Puyol injured and Eric Abidal recuperating from surgery on a liver tumor . He must decide whether to use midfielder Sergio Busquets or draft in Gaby Milito in central defense . But all eyes will be on the free-scoring Barcelona attack , led by Lionel Messi , who has scored a club record 48 goals this season . Messi , who was in superb form in the earlier league victory , will be looking to score for the first time against a team managed by Mourinho . In other La Liga action at the weekend , Valencia travel to bottom side Almeria on Saturday looking to cement third place after their 5-0 rout of local rivals Villarreal last Sunday .
Real Madrid and Barcelona meet in first of four El Clasico showdowns in 18 days . Real manager Jose Mourinho refuses to answer media questions ahead of match . Barcelona bidding to complete sixth straight win over their arch rivals . Further clashes coming up in Copa del Rey final and Champions League semis .