Anything could happen but here are four things that (almost) definitely will as Spain goes clasico crazy for 18 days.
Messi to finally score against MourinhoIn nine matches against Jose Mourinho, Leo Messi has never scored but with four chances inside three weeks and in incredible form, even by his standards, now is surely the time to break the curse.
He made his debut for Barcelona in a friendly in November 2003 against a Mourinho-led Porto. Barcelona won the game 2-0 with Messi playing 15 minutes but he failed to score.
Two years later, Mourinho accused him of play-acting to get Asier Del Horno sent off as Barcelona beat Chelsea 2-1 in the last-16 first leg. The Argentine didn't score. In the return leg that year he also failed to score in the 1-1 draw that saw Barca go through.
Real deal: Barcelona superstar Lionel Messi must surely end his goal drought against Jose Mourinho
In the 2006-07 season Barcelona and Chelsea were drawn together in the group stage of the tournament. But Chelsea won 1-0 in London and he failed to score in the 2-2 draw at the Nou Camp.
Last season he played in the 0-0 group stage match with Inter and then failed to score in both semi-final legs as Barca crashed out. And although he has happier memories of this season's league game at the Nou Camp last November he again failed to score in the 5-0 win.
He has 29 goals in 28 league games; nine goals in 10 Champions League games and 10 goals in eight domestic cup games. He is top scorer in all three competitions so surely in one of them he will find the net for the first time ever against his old foe.
No Barcelona clean sweepBarca have won the last five clasicos, only the great Madrid side of Alfredo Di Stefano and Ferenc Puskas won six on the bounce.
It's been a clean sweep for Guardiola since taking over in 2008 and his 5-0 thrashing of Jose Mourinho's team last year topped the lot because it silenced those arguing that everything would be different now that the Special One was in charge of Real Madrid.
Mourinho got the better of Guardiola in the semi-finals of last year's Champions League with Inter now he needs to repeat that feat at the same stage of the competition, or win the Spanish Cup final or at least beat them in the league on Saturday.
Head-to-head: Mourinho must outwit Barca boss Guardiola and guide Real Madrid to a famous clasico win
It will be his 50th match in charge at the club on Saturday. He has won 38 of his 49 games to date.
He has just clocked up 500 games as a coach with a staggering 67 per cent win rate. Only one man has a better percentage - Guardiola with 74 per cent in 171 matches in charge.
Remember what Cloughie said about not necessarily being the best but being in 'the top one'. Mourinho needs a clasico win over Guardiola - four-out-of-four for Barcelona is unthinkable.
Ronaldo to finally score against BarcelonaRonaldo's record against Barca is almost as bad as Messi's against Mourinho. He is yet to score in a clasico and failed to find the net in three games against them playing for Manchester United.
He has also struggled in matches against Spain and the common factor in those failures is Carles Puyol, who will be missing from at least the first two encounters.
Stopped in his tracks: Cristiano Ronaldo is yet to score for Real Madrid against Barcelona
With Barcelona's top defender out and their next best, Eric Abidal, still recovering from the successful operation to remove a tumour from his liver, Pique will be partnered by one of three players over the next four matches.
They are Gabi Milito, who almost left in January because of limited opportunities, midfielder Sergi Busquets or Javier Mascherano, who is suspended for the league game but played in central defence against Shakhtar Donetsk in midweek and could do so again in the semi-finals. Either way it ought to give Ronaldo the advantage as he looks to break his duck.
The four games will not finish XI against XIAs sure as the pitch will be green, the cards will eventually be red. Sergio Ramos was sent off in November and tempers are bound to flare again even between Spain team-mates.
'The key to beating Barcelona will be to finish with 11 players' said Mourinho this week. 'I never seem to manage it.'
Followers of Florentino Perez's first time in charge at Real Madrid, especially the period 2003-2006, can't help but see his likeness in the Chelsea owner Roman Abramovich.
Perez had grown bored with success under an established and respected coach - Vicente Del Bosque who had delivered the 2002 Champions League and the 2003 league - and embarked on a hiring and firing spree that lasted three seasons and saw him go through six coaches.
It was also the era of scattergun big-name signings. Barcelona fans called it the nombres over hombres approach - names being more important than getting the right men for the job.
Watch and learn: Abramovich must avoid repeating the same mistakes as Madrid supremo Perez (L)
In 2003 the club signed David Beckham when they already had Luis Figo in the same position. Chelsea it seems will sell Didier Drogba at the end of the season. Real Madrid kept Figo, played Beckham out of position, and won nothing for three years.
Coaches were regularly told what teams to pick - or in several cases sacked for going their own way. And divide and rule prevailed with sporting directors and coaches were thrown together and played off each other - anything to prevent the buck stopping with the president.
Roman Abramovich has turned Chelsea into a European super power now he needs to put down the old Perez handbook, or at least turn to the page where he stops trying to run the team and pays a top coach to do it for him.
Only one doubt about Manchester United's plans to sign the brilliantly talented David De Gea. He's 20 now, so will probably be beginning to peak as a keeper in five years time.
Isn't it after about five years that players signed from Spain or Portugal start feeling homesick and want to sign for Barcelona or Real Madrid?
No way, Jose! Mourinho rubbishes speculation of a summer switch to Man CityRonaldo dreaming of Wembley final clash against old club Man UnitedDe Gea to sign five-year Man United deal as Atletico agree ?17.8m exit
Explore more:People: David Beckham, Sergio Ramos, Alfredo Di Stefano, Javier Mascherano, Jose Mourinho, Florentino Perez, Leo Messi, Didier Drogba, Roman Abramovich Places: Barcelona, London, Madrid, Portugal, Spain