Barcelona's straightforward victory over struggling Cadiz 2-nil restored their eight-point lead over the next team in La Liga.
After Robert Lewandowski's header was pushed off the line late in the first half, Sergi Roberto gave Barca the lead with a rebound.
Lewandowski was picked out by Roberto and blasted home a beautiful shot from the edge of the box three minutes later.
Both players have not scored a league goal at the Nou Camp since a 4-0 victory over Athletic Bilbao on October 23.
Lewandowski's crossbar miss gave Xavi's team opportunities to extend their lead.
The only player to accomplish that figure in less games since the turn of the century is Cristiano Ronaldo, who did it in 17 games in 2009–10. The Poland striker has scored 15 goals in his first 19 La Liga appearances.
Barcelona has won its last seven La Liga games and is undefeated in 13 games. Real Madrid, their closest competitor for the title, defeated Osasuna 2-0 on Saturday.
With a record-breaking 17th clean sheet of the La Liga season after 22 games (beating Deportivo de La Coruna's 16 from 1993–1994), their impressive defensive performance also keeps up.
Cadiz, who had two goals by Roger ruled offside, are still two points above the drop zone.
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