(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 isn'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 won'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.