MADRID - The 168th La Liga "Clasico” between in-form Real Madrid and an erratic Barcelona could see the table-toppers take a big step towards winning the title and sound the death knell for the champions bid for a fifth triumph in six years.

Leaders Real host their arch rivals at the Bernabeu on Sunday in one of soccer’s most emotive occasions, featuring a clash of the world’s two richest clubs, the two best players - Real’s Cristiano Ronaldo and Barca’s Lionel Messi - and watched by hundreds of millions around the world.

Real, on 70 points with 10 games left, are in much the better shape going into the match and have put together an unbeaten run of 31 matches in all competitions since they lost 2-1 at Barca in La Liga at the end of October.

Barca, four points behind Real in third and a point adrift of surprise packages Atletico Madrid in second, slipped to surprise recent defeats at Real Valladolid and Real Sociedad and badly need a win to reignite their campaign.

The stage is set for another grand spectacle, when some of the game’s most expensive and best-paid talent, including the likes of Gareth Bale and Karim Benzema for Real and Neymar and Alexis Sanchez for Barca, will seek to make their mark.

Like Ronaldo, who has netted 12 times against Barca since joining Real in 2009, Messi has been on scintillating form in recent weeks and the Argentina forward can overtake Real great and compatriot Alfredo Di Stefano as the leading marksman in "Clasicos” if he can score a 19th goal on Sunday.

TREBLE CHASERS

"Now is the crunch time in the season, when things are won and lost so we need to keep our performances up and keep winning games,” Bale said after Real secured their place in the Champions League quarterfinals on Tuesday.

"We will treat the game against Barcelona as just another match,” added the Wales winger, who played just over an hour of his first "Clasico” at the Nou Camp in October without making much of an impact.

Real coach Carlo Ancelotti had a patchy start to his first season but has since moulded his hugely talented squad into a unit that has a genuine chance of becoming only the second Spanish club after Barca to secure aChampions League, La Liga and King’s Cup treble.

Sunday’s game is also a warm-up for the Cup final between Real and Barca in Valencia on April 16 and they could be drawn to play each other in the last eight of Europe’s elite club competition early next month.

Barca also have a new coach in Gerardo Martino, who comes from Messi’s home city of Rosario, but a lack of consistency in recent months has seen them surrender the La Liga lead.

The club has been in institutional turmoil over Neymar’s transfer from Santos in the close season, with presidentSandro Rosell stepping down amid allegations of misappropriation of funds and tax evasion.

Neymar has been in poor form since the turn of the year, while Real’s marquee signing Bale, who joined from Tottenham Hotspur for a record fee of 100 million euros ($139 million), has been increasingly impressive.

FOCUSED, UNITED

However, Barca can still repeat the treble they won under Pep Guardiola in 2009 and forward Pedro said they were full of confidence after dispatching Manchester City in the Champions League round of 16.

 "The team is focused, concentrated and united,” the Spain international said on the club’s website (www.fcbarcelona.es).  "In the important games the team has performed very well and at a very high level,” he added.

Real have had the upper hand in recent home games against Barca, winning once in the league and once in the Spanish Super Cup and drawing in the King’s Cup.

They have won 70 of 167 La Liga meetings overall with the Catalan club going back to 1929, losing 65 and drawing 32.