LaLiga leaders Real Madrid were left frustrated in a 0-0 draw at Rayo Vallecano on Sunday, giving champions Barcelona a chance to close in on them.
Xabi Alonso's side moved five points clear of Villarreal in second and six ahead of the third-placed Catalans, who visit Celta Vigo later on.
Rayo battled strongly in the derby clash, and although Real Madrid had the better chances, the hosts also had opportunities to win a scrappy game.
They managed to limit LaLiga top scorer Kylian Mbappe's influence, while keeping Vinicius Junior and Jude Bellingham safely at arm's length as well.
Madrid were hoping to bounce back from their Champions League defeat by Liverpool at Anfield on Tuesday, but Alonso's side dropped points for only the second time this season in the league.
Inigo Perez's Rayo came out fired up and threatened first, when Andrei Ratiu fired straight at Madrid goalkeeper Thibaut Courtois.
HOSTS HOLD FIRM
After that, Madrid began to take control, but the hosts, in mid-table, held firm at their Vallecas stadium.
Raul Asencio headed wide when well-placed, and Augusto Batalla made a fine instinctive save to push away a Vinicius effort.
Rayo starved Madrid superstar Mbappe of the ball, with the Frenchman unable to threaten in his usual manner.
Madrid coach Alonso sent on Eder Militao for the booked Dean Huijsen at halftime, wary of Isi Palazon and Jorge de Frutos' threat.
De Frutos came close early in the second half when he nipped in at the near post between two defenders to reach Pacha Espino's cross and hit the side netting.
Bellingham forced Batalla into a good save at his near post after a lovely touch to bring the ball down as he tried to continue his recent strong goalscoring form.
Mbappe had his first effort on the hour mark as Rayo let him loose for the first time, whipping a shot wide of the far post.
Batalla beat away a Fede Valverde drive from distance, while Alvaro Garcia fired over at the other end as Rayo looked to snatch victory.
Alonso sent on Trent Alexander-Arnold in the final stages as the England international continues finding fitness after injury.
Madrid midfielder Arda Guler came close to breaking the deadlock in stoppage time as his effort was deflected behind, but Rayo survived to claim a point.
