Atletico Madrid stayed hot on the heels of second-placed city neighbours Real Madrid when Radamel Falcao netted his 25th goal of the La Liga campaign in a scrappy 1-0 win at mid-table Sevilla on Sunday.
Diego Simeone's Atletico can overhaul Real, whom they play in next month's King's Cup final, if they beat them by more than two goals at the Calderon next weekend.
However, they will be without combative Brazil forward Diego Costa, who was booked on Sunday and will miss the game through suspension.
In a poor-quality and bad-tempered match at Sevilla's Sanchez Pizjuan stadium, littered with yellow cards, diving and play-acting, neither side created much danger until Falcao struck in the 76th minute.
Adrian chipped a cross to the far post and when fellow substitute Raul Garcia volleyed towards goal Falcao nipped in to poke the ball into the corner of the net.
Sevilla pressed for an equaliser and Alvaro Negredo nodded just wide and midfielder Ivan Rakitic curled a free kick on to the crossbar but Atletico held them at bay.
"We defended well, we took our chance and they are three priceless points that keep us in the fight for second place," Adrian said in an interview with Spanish television broadcaster Canal Plus.
"It's bad news (that Diego is suspended) because he has been putting in some spectacular performances but those who are available have to be prepared and the coach will decide who is in the team," he added.
The victory stretched Atletico's lead over fourth-placed Real Sociedad to 13 points after the Basque side were earlier held to a 0-0 stalemate at Osasuna.
The result gave Valencia a chance to leapfrog Sociedad into Spain's fourth Champions League qualification berth when they clash in San Sebastian next weekend.
The surprise packages in Spain's top flight this season, Sociedad created plenty of chances at Osasuna's Reyno de Navarra stadium in Pamplona but the relegation-threatened home side held on for a point that left them in 15th on 32 points.
Sociedad have 55 points in fourth, two ahead of Valencia after their 5-1 win at home to Malaga on Saturday lifted them above the Costa del Sol club to fifth.
Leaders Barcelona took another step towards their fourth title in five seasons when a late strike from Cesc Fabregas gave them a 1-0 win at home to Levante on Saturday.
Barca have a 13-point lead over Real, who beat visiting Real Betis 3-1, and can wrap up the title next weekend if they win at Athletic Bilbao and Real lose at Atletico.
In Sunday's earlier kickoffs, Espanyol climbed to 10th, a point ahead of 11th-placed Sevilla, thanks to a 2-0 win at nine-man Getafe.
Deportivo La Coruna, who seemed doomed to relegation a few weeks ago before embarking on a four-match winning run, earned another precious point in a 1-1 draw at home to Athletic Bilbao.
Depor are 16th on 30 points, two above the drop zone, while Bilbao, who have been unable to reproduce the form that took them to the final of the Europa League and the King's Cup last season, are 14th on 36 points.
Photograph: Marcelo del Pozo/Reuters