Neymar scored his first league goal and helped Barcelona ease past Real Sociedad 4-1 in the Spanish league on Tuesday and stay perfect after six rounds.
Atletico Madrid also stayed perfect thanks to goals by Diego Costa in a 2-1 win against Osasuna, giving it 18 points, although Barcelona stay top with its better goal differential.
Neymar opened the scoring in the fourth minute before two more goals from Lionel Messi and Sergio Busquets inside 25 minutes left Real Sociedad reeling at the Camp Nou.
The Brazil forward made the most of hesitation between two Sociedad defenders and goalkeeper Claudio Bravo to rush forward and poke the ball home for his first goal since joining the champions in the close season for 57 million euros ($76 million), .
"It doesn't matter that it was a scrambled goal, what is important is that it went in," said Neymar. "The team is getting better all the time."
Messi lunged headlong four minutes later to score past Bravo from Neymar's cross for his seventh league goal this season.
A minute later Bravo was forced to sprint forward and punch away a head-high ball as Neymar arrived alone into the penalty area.
Sociedad captain Xabier Prieto fell to the ground clutching his right thigh and had to be substituted in midfield by Imanol Agirretxe in the 21st.
Busquets scored Barcelona's third two minutes later after the ball had bounced off the crossbar from Messi's close-range shot.
Mascherano was substituted at half time by Marc Bartra, and Barcelona upped the pressure on Bravo, who was forced to save twice and watch another shot go just over the bar in a 10-minute spell.
Sociedad pulled one back when Agruirretxe beat Gerard Pique and passed the ball across the goalmouth for Alberto de la Bella to tap into goal past a stranded Victor Valdes in the 64th.
"One of our starting premises was not to allow them to score in the first few minutes, which is something we've done in other years, and look what happened," said de la Bella. "Playing like this in the Camp Nou makes it very difficult for us."
In the 76th minute, Messi dribbled past three defenders before crossing to Bartra who flicked the ball into goal to complete the rout.
Costa scored his sixth league goal of the season for Atletico when he deftly flicked in a cross in the 18th and he then doubled his tally with a sublime header from a Jorge "Koke" Resurreccion assist in the 25th.
Oriol Rieira pulled one back for Osasuna in the 43rd.
Atletico coach Diego Simeone chose to rest striker David Villa and began with an all-Brazillian attack of Baptistao and Diego Costa.
Elsewhere, Levante drew 1-1 with Valladolid. Baba Diawara opened the scoring for Levante in the 35th minute and Javier Guerra equalized six minutes later.
Malaga beat Almeria 2-0 with goals by Fernando Tissone and Francisco Portillo.
On Wednesday Real Madrid travels to Elche, Sevilla hosts Rayo Vallecano and Granada plays Valencia.