Barcelona's �60m striker Zlatan Ibrahimovic stepped off the bench to score the only goal of a fiercely contested El Clasico against Real Madrid and move Barca back to the top of the league.
Barca, who started the game a point behind their arch rivals, finished the game with 10 men when Sergio Busquets was shown a second yellow card just after the hour mark.
But by that time they had a lead courtesy of Ibrahimovic's brilliantly-struck left-foot volley from Dani Alves' right-wing cross - the Swede netting just minutes after coming on for Thierry Henry.
Real created the better of the chances in the Camp Nou, but paid for their wastefulness, with substitute Karim Benzema most culpable as he ballooned haplessly over with only five minutes left.
Barca captain Carles Puyol twice crucially denied Marcelo with last-ditch blocks as the Brazilian prepared to shoot and, despite a fraught last few minutes, Barca held on for victory.
Real ended the game with 10 men too, as Lassana Diarra was booked for the second time in the last minute after a reckless kick out at Xavi.
Barca move two points ahead of Real, but there is plenty of life left in this Spanish league season and the Catalans, who swept all before them last year, will know they face a real threat to their La Liga crown in Manuel Pellegrini's Real.
The last time these two teams met Barca thrashed Real 6-2 in the Bernabeu in May as they romped to the league title as well as picking up the Champions League and Spanish Cup.
Real hit back in the summer, splashing out nearly �250m as Florentino Perez, in his second spell as president, began the second era of Galacticos by signing Cristiano Ronaldo, Kaka, Benzema and Xabi Alonso, among others.
Real's football this season has rarely hit the heights, but they have been instantly effective and went into the game a point ahead of Barca at the top of La Liga.
It was not difficult to see why, as the visitors caused Pep Guardiola's team far more problems than they have become accustomed to on their own turf, in front of 98,000 baying fans at the Camp Nou.
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