Imanol Agirretxe scored twice as Real Sociedad cruised to a 3-0 win over Real Zaragoza.
The hosts were dominant from start to finish and had the points sewn up by half-time after three first-half goals.
Agirretxe got the first as he volleyed into an unguarded net after Roberto had parried David Zurutuza's cross on 18 minutes.
Three minutes later Carlos Vela made it two as his deflected effort wrong-footed Roberto and Agirretxe tapped home his second after Alberto de la Bella's cross had found him free at the back post.
Vela and Joseba Llorente should have added more goals in the second period but Zaragoza's miserable evening was completed when Maurizio Lanzaro was sent-off for a second bookable offence.
Zaragoza had produced a remarkable comeback to beat Villarreal last weekend and maintain some hope of avoiding relegation but they lacked the same belief and determination at Anoeta as Sociedad took advantage of some woeful defending.
The opener arrived on 18 minutes as good play down the right found Zurutuza free inside the area and when Roberto could only parry his fierce cross, Agirretxe was on hand to turn the ball home.
Vela then doubled the hosts' advantage as he collected Lanzaro's poor clearance at the edge of the area and the Mexican's shot was deflected over the helpless Roberto and into the net.
And it was three before the break as more poor defending allowed De la Bella acres of space on the left and his pinpoint cross was gratefully tucked away by Agirretxe at the back post.
Vela passed up two good opportunities to double his tally as Roberto did well to turn away the Arsenal loanee's attempted lob before making a more comfortable save after the Mexican had created space for himself inside the area with a neat turn.
Substitute Llorente was next to threaten as Sociedad continued to open up the visiting defence at will but he shot straight into Roberto's legs and then, after Lanzaro had seen red for leading with his elbow in an aerial challenge, squandered an even better opportunity as he pulled his effort wide when clean through on goal.
However it matter little as Sociedad moved alongside Atletico Madrid and Espanyol in mid-table on 33 points, whilst Zaragoza remain rooted to the foot of the table, nine points off safety.
