Barcelona arguably put up their most dominant performance of the season as they decimated Real Sociedad 6-1 on their own turf.
Barcelona manager Ronald Koeman named an unchanged 11 from the side that saw off Huesca last Monday. He, however, he made a minor tweak in attack, with Lionel Messi and Ousmane Dembele leading the line while Antoine Griezmann played in the hole behind.
A very open start to the game saw both sides fashion good chances, but it was Real Sociedad who came closest to breaking the deadlock.
Alexander Isak showed great strength and pace to hold off the challenges of several Barcelona defenders before releasing a shot in the box that was saved by Marc-Andre ter Stegen.
Sergino Dest went closest to finding the target next, as his cross from the edge of the area was tipped over the bar by Alejandro Remiro with a wonderful save.
Barcelona broke the deadlock in the same sequence as Messi found Jordi Alba down the left flank and the Spain international sent a square ball into the area.
Dembele saw his shot saved at point-blank range by Merino but Griezmann was on hand to convert the rebound against his former side. It was a well-deserved lead, as the Blaugrana had clearly been the dominant side in the minutes leading up to the goal.
Real Sociedad almost had an instant equalizer, as Ter Stegen almost played his side into trouble. The Barcelona keeper's mishit pass was pounced upon by Mikel Oyarzabal who subsequently found Isak with a pristine through ball. Ter Stegen redeemed his image with a smart save down to his right from Isak's shot.
The visitors doubled their lead right on the stroke of halftime. A quick break saw Messi charge forward with the ball and he had two options either side of him but elected to thread the pass to Sergino Dest who scored Barcelona's second with a precise low shot.
Two quickfire goals at the start of the second half saw Barcelona quadruple their lead.
First, Jordi Alba burst forward down the left flank to the byline. He then sent a routine cross into the area that found Sergino Dest to score his second goal of the game in the 53rd minute.
Just three minutes later, Sergio Busquets sent a perfectly-weighted lofted pass in the area and Messi showed great skill to dink the ball over the onrushing Merino.
From then on, it was one-way traffic as the visitors asked all the questions of Real Sociedad.
They had the ball in the back of the net once again and this time it was Dembele who latched onto a through pass and found the bottom corner with a right-footed shot. The goal, however, was chalked off for a foul in the buildup after a VAR review.
The France international was not to be denied five minutes later. Dembele picked up the ball near the halfway line and skipped across the Sociedad defense before slotting past Merino with his left foot.
Ander Barrenetxea got on the scoresheet soon after with a contender for goal of the season. The 19-year-old showed great skill to evade two Barcelona challenges on the halfway line and combined brilliantly with Carlos Fernandez before rifling an unstoppable shot into the top corner from 22 yards.
Lionel Messi rounded off the scoring in the first minute of injury time when he tapped home from close range. Jordi Alba was once again the provider with a square pass from the left flank.
The victory extends Barcelona's unbeaten run to 18 games in the league. Here are five talking points from the fixture.
#5 Barcelona send statement of intent to their La Liga rivals
Atletico Madrid held on by the skin of their teeth for a 1-0 victory over Alaves earlier on Sunday evening. Real Madrid saw off Celta Vigo 3-1 away from home on Saturday and these results put pressure on Barcelona to get the job done.
Despite some nervy moments early in their clash with Real Sociedad, it was an entirely convincing performance from the Blaugrana and they were deserved winners based on the overall balance of play.
The victory saw Barcelona close the gap at the summit back to four points and the impetus is very much with the Catalan side heading into the international break.
Beyond the victory, the manner in which they saw off one of La Liga's better sides sent a statement of intent about their claim to the La Liga title.
The victory means Barcelona have won their last five league games consecutively. They have also won their last nine away league games, with 26 goals scored and six clean sheets kept.
#4 Real Sociedad looking over their shoulders in quest for European qualification
Real Sociedad started the season brightly and many tipped them as outsiders for a top four finish.
However, the contenders have since been separated from the pretenders but the Basque outfit are still favorites to secure Europa League qualification.
Having seen their nearest challengers Real Betis and Villarreal pick up victories earlier in the matchday, Imanol Alguacil's side faced the daunting task of matching this result against the league's most in-form team.
That failed to happen and a whitewash on home turf means that Real Sociedad are level on points with Real Betis, with Villarreal just two points behind in the race for a top six finish.