BARCELONA, Dec 6 (Reuters) - Real Madrid beat an over-cautious Barcelona side 2-1 on Saturday to claim their first league win at the Nou Camp in 20 years and aggravate the crisis engulfing their old rivals.

Real needed a slice of luck in a game that featured only isolated moments of good football, with both their goals from Roberto Carlos and Ronaldo being deflected past exposed keeper Victor Valdes.

They also had to withstand a bit of pressure at the end after Patrick Kluivert had pulled one back for the Catalans with a point-blank header from a corner seven minutes from time.

Real were well worth their victory, though, in what was a subdued Spanish derby compared to the mayhem of last year's meeting, when the referee was forced to lead the players from the field as missiles rained down from the crowd.

The result took Real back three points clear at the top of the table, and a whopping 13 points ahead of Barcelona with 15 games played.

It also served to underline the fact that while Barcelona may be Real's greatest historical rivals, they are now hardly capable of troubling them on the field.

WILL TO WIN

"We deserved the win," Real coach Carlos Queiroz told reporters. "Barcelona tried to take hold of the midfield in the first half and they did cause us some problems.

"We came out with the will to win, however, and we might well have gone further ahead.

"It's only natural that Barcelona came back in the second half. They were at home and they were losing."

Barcelona went into the match on the back of a 5-1 defeat by Malaga in the league in midweek.

They picked up in the same abject form as the players consistently misplaced their passes and pumped aimless balls forward for Kluivert to chase.

Coach Frank Rijkaard was unable to call on injured Brazilian playmaker Ronaldinho but he did himself few favours with his team selection.

The Dutchman, under increasing pressure from the voracious Catalan sports media, opted to leave talented Argentine forward Javier Saviola on the bench and pack his side with out-of-form defensive midfielders.

Real could hardly believe their luck and Zinedine Zidane and David Beckham set about carving up Barca.

"I think it's only normal to seek a bit more security after losing like we did against Malaga," Rijkaard said of his tactics.

"We did succeed in limiting Real Madrid to that one chance in the first half and that's to our credit."

By Kevin Fylan