Factbox - Key head-to-heads in the La Liga 'Clasico'

(Reuters) - Key head-to-head battles in Sunday's "Clasico" between Barcelona and Real Madrid at the Nou Camp (2000 GMT): LIONEL MESSI v CRISTIANO RONALDO Messi, 27, and Ronaldo, 30, are two of the most consistently lethal goalscorers in football history and a match rarely passes without them getting on the scoresheet. Portugal captain Ronaldo, who has scooped the last two FIFA Ballon d'Or awards after four consecutive wins for the Argentina skipper, had a blistering start to the campaign before his form tailed off and he has netted 30 goals for Real in La Liga this season. Messi recently overtook Ronaldo and is the leading scorer on 32. Both players have the freedom to roam, although their styles are very different. Messi plays with schoolboy enthusiasm, making darting runs and exchanging quick passes with team mates. The muscular Ronaldo is more of a showman, charging around the pitch, and his powerful, swerving shots are a threat from any range. NEYMAR v GARETH BALE Neymar has had an excellent second season at Barca after a fine performance for Brazil at the World Cup. Considered more of an out-and-out goal scorer than Bale, the 23-year-old's on-field partnerships with Messi and fellow forward Luis Suarez have flourished this term and Neymar has 17 goals to his name in La Liga, three in the Champions League and six in the King's Cup. Bale, 25, has yet to justify his record price tag and was whistled by Real fans in recent weeks after going nine games without scoring. However, he bounced back with a double against Levante at the weekend and has a habit of coming good on the big occasions. LUIS SUAREZ v KARIM BENZEMA France forward Benzema, 27, is an established force in Spain and has the firm backing of Real coach Carlo Ancelotti, while Uruguay's Suarez, 28, who joined Barca from Liverpool in the close season, still has plenty to prove. He had a slow start to his Barca career after making his debut in October's 3-1 'Clasico' defeat at Real following a four-month ban for biting an opponent. He has started to move up the gears since the turn of the year and looks to be getting close to his lethal best. Benzema, who has also been targeted by disgruntled fans at the Bernabeu in previous years, is enjoying one of his most successful seasons since joining Real in 2009. As well as scoring goals, the pair are known for their work rate off the ball, tracking back to challenge for possession and making intelligent runs that open up space for team mates. IVAN RAKITIC v TONI KROOS The two midfielders, gifted passers who operate in slightly different central roles, will be expected to dictate play for their respective teams and their success or failure could go a long way to deciding the game's outcome. Both are in their debut seasons with their clubs after Germany's Kroos joined Real from Bayern Munich and Rakitic of Croatia moved to Barca from Sevilla. Kroos, 25, was a key performer for Germany in their triumph at the 2014 World Cup and has made sure that Real have not missed former Spain midfielder Xabi Alonso, now at Bayern. While Kroos mainly excels at long-range shooting, Rakitic, 27, can also score from distance but has the additional ability to time runs into the box to finish off one of Barca's trademark passing moves and is generally more effective than the German at playing the killer pass to create a scoring chance. CLAUDIO BRAVO v IKER CASILLAS Real captain Casillas has endured a torrid time over the past couple of years and was widely criticised when Spain crashed out of the 2014 World Cup at the group stage before being whistled at the Bernabeu by disgruntled home fans for most of this season. Ancelotti has stuck with the 33-year-old despite the arrival of Costa Rica keeper Keylor Navas. Chile keeper Bravo, who Barca recruited from Real Sociedad to replace Victor Valdes, made a record-breaking start to his stint at the Nou Camp and has conceded only 16 goals in 27 La Liga outings. Similar in stature and style to Casillas, the 31-year-old is perhaps more accomplished at dealing with crosses than his Real counterpart and his ball-playing skills mean he has settled comfortably into a Barca team that likes to begin their attacks from the back. (Compiled by Iain Rogers, editing by Toby Davis)