Xavi rescues point for Barca at Sevilla
Barca had a chance to move to within three points of Real, who host Valladolid on Sunday, but faced an uphill battle after Diego Capel put an impressive Sevilla ahead in the first half.
They improved after the break and 14 minutes from time Xavi equalised to leave the Catalans on 48 points, five short of Real.
"Real are the strongest team at the moment. We are in three competitions and have to concentrate on getting our own work done. We have to keep on working hard and accumulating points," Barca coach Frank Rijkaard said.
Earlier on Saturday, Guillermo Franco snatched a goal in added time for Villarreal to give them a 1-0 victory at lowly Real Murcia. They climbed to third with 42 points.
Murcia had the better of a poor game until Mexican striker Franco, who appeared to be offside, controlled a ball over the top and slipped it past furious home goalkeeper Antonio Notario in the final minute.
In Saturday's other game, Nigeria striker Ikechukwu Uche rescued a point for Getafe in a 1-1 draw at Deportivo Coruna.
Sevilla took the game to Barca and Daniel Alves stung Victor Valdes's fingers with a fierce drive from a free kick early on.
Their swift breaks continually unsettled the visiting defence and Valdes had just saved a close range volley from Frederic Kanoute when Sevilla took the lead.
Alves released Jesus Navas in the area and his low cross from the right was turned home at the far post by 19-year-old winger Capel.
Barca finished the half penned inside their own area and Rijkaard turned to substitute Ronaldinho at halftime to try and get his side back into the game.
But it was the irrepressible Lionel Messi who provided the pass for midfielder Xavi to burst into the area and fire underneath Andres Palop in the 76th.
Two minutes later Sevilla lost Mali midfielder Seydou Keita to a second yellow card but Barca failed to make their extra man count in an exciting finale in which either team could have won.