It is the most recognisable fixture in world football and once again on Saturday Barcelona and Real Madrid will go head to head in El Clasico.

Real Madrid have often appeared the club in crisis ahead of recent meetings, however the tables have turned and Luis Enrique's side are in danger of affording their rivals a nine-point lead at the top of La Liga if they fall to defeat.

Here, Sportsmail takes a look at the 10 key questions ahead of Saturday's battle at the Nou Camp...

1. Should Real Madrid be favourites?

The bookmakers still have Barcelona as favourites for the game despite their recent form, which has seen them lose to Manchester City and draw with Malaga, Real Sociedad and Hercules.

Even some of their victories have disappointed fans, who saw the Catlans battered by Sevilla in the first half before they turned things around in the second to win 2-1, while they expected more than a 1-0 win over lowly Granada.

Real Madrid, meanwhile, are the only undefeated team in La Liga and recently thrashed rivals Atletico Madrid 3-0 in the derby, the best result since Zinedine Zidane took charge.

They are Europe's form team and it would be no surprise if they came away with three points from El Clasico.

2. Will Andres Iniesta be ready?

Part of the problem with Barcelona recently is that since October 22, Andres Iniesta has been watching from the sidelines. A bad tackle from Valencia's Enzo Perez left the midfielder nursing a knee injury and Barca without their main key for unlocking opposition defences.

The good news for the Catalan club is their captain will start on Saturday afternoon. Luis Enrique said he would have given him some minutes in the Copa del Rey draw with Hercules on Wednesday night if he hadn't been suspended.

The only real doubt will be if he is ready for such an intense game. History shows us the 32-year-old is capable of managing himself intelligently - he went into the 2009 Champions League final against Manchester United still carrying an injury, with instructions not to shoot, and still ran the game.

Enrique's main injury concern, however, is Jordi Alba, who is struggling with ankle and knee problems.

3. Should Cristiano Ronaldo play as a No 9?

The decision to utilise the Portuguese forward as the central striker against Atletico Madrid was a Zinedine Zidane masterstroke as he scored a hat-trick and put in his best performance in recent memory.

While Ronaldo likes having the freedom of playing on the left with permission to drift into the area, he is more useful to his team up top.

It also meant Gareth Bale could switch to the left, with the Welshman working much harder than Ronaldo when it came to defensive duties.

However his injury leaves Zidane with a problem. He may be forced to pick Ronaldo on the left, with neither Alvaro Morata or Karim Benzema the type of player who works well in wide positions.

4. Who will replace Gareth Bale?

The Welshman will be out for up to four months after undergoing ankle surgery. That means the 'BBC' attacking line will be broken up, with Lucas Vazquez likely to replace him.

The Spanish winger is far from a household name but has performed well when asked to step in for one of his more illustrious colleagues.

Zidane is a big fan of the right winger who works much harder to get back than others. When Madrid don't have the ball he will be required to play as a midfielder, rather than a forward.

5. Will the 'MSN' dazzle at last?

Only Lionel Messi has been playing close to his best this season out of Barcelona's trio of forwards. The Argentine has been in spectacular form since returning from injury, his goals saving the team on several occasions.

Luis Suarez's slump in form has been the most alarming, the Uruguayan appearing frustrated and unable to sink his teeth into games when compared to his dominant displays last season.

Neymar has struggled for goals but at least is still creating them, with his brilliant run setting up Messi against Real Sociedad last weekend.

After defeat by Sociedad in January last year, the trio came out swinging and destroyed Atletico Madrid. Once again after humiliation at Anoeta they face a capital club. If they can pull themselves together, they can shine once more.

6. Who will have more of the ball?

Traditionally the Catalans dominate the ball, while Madrid are usually quite happy to relinquish possession for periods before striking their opponents on the counter.

However, in the Luis Enrique era possession hasn't been a priority and Barcelona have actually struggled to keep hold of the ball.

Enrique's only aim will be to win, but if Madrid came to the Nou Camp and dominate proceedings, the purists would be horrified.

7. Who is going to make an impact in their first Clasico?

Barcelona's Paco Alcacer was meant to offer the team a new option if the MSN forward line wasn't firing, but the 23-year-old has yet to even find the net since his move from Valencia.

Samuel Umtiti is the most likely to have an impact for the hosts. If he is fit to play then he may be teamed up with Gerard Pique in an attempt to stop Ronaldo, who has got the better of Javier Mascherano on more than a few occasions.

Madrid, meanwhile, only signed Morata for their first-team this summer and he may not even feature with Benzema preferred. Mateo Kovacic, who has yet to have his frist taste of the fixture, will look to build on his recent good form in place of Casemiro, who is building fitness after injury. There is a chance the Brazilian could start ahead of Isco though, if Zidane looks to shore up his defensive line.

8. Will it be Messi or Ronaldo who decides the game?

It goes without saying, whichever of the pair delivers will have a massive impact on the game. Messi has actually failed to score in the previous five meetings, last netting when Tata Martino was in charge.

He has gone 400 minutes without finding the net against Real Madrid, and this is one of the few records that he could probably do without.

Ronaldo, meanwhile, settled the last Clasico, striking late on at Camp Nou to earn Real Madrid victory. Although it served for nothing in the league as Barcelona triumphed, it set Madrid on a positive path towards Champions League victory.

9. Where are the weak spots in both sides?

Barcelona have been fragile recently with too much space between Sergio Busquets and his midfield partners. Iniesta returning should help fix that, but if Madrid can isolate the defensive midfielder they can not only stop Barcelona passing out from the back but also win possession high up the pitch.

Madrid, meanwhile, have been weak defensively for most of the season and captain Sergio Ramos has been particularly poor in his own penalty area, giving away cheap fouls. Luis Suarez will be looking to capitalise on that.

10. If Real Madrid win is it game over for Barcelona in the title race?

A nine-point gap would be huge, but not insurmountable. Real Madrid have to go to Japan to compete in the Club World Cup in December and that always has an adverse effect on teams.

Barcelona's tiredness at the crucial moment of the campaign last season was no doubt in part due to their participation in the winter tournament.

Barcelona came close to throwing away a 12-point lead in La Liga and only won the title by going on a winning run of five games to see out the 2015-16 season, so making up nine points can be done. However, defeat in the Clasico would make things extremely difficult and could do a lot of damage to morale in Catalonia.