And it was the usual suspect Lionel Messi that opened the scoring in the 27th minutes as he showcase his brilliant free kick ability, from a long distance.
Should they pick up a point or more, they will equal Real Sociedad's streak across 1978/79 and 1979/80, and move seven games away from the first unbeaten La Liga season in history. He doubled his side's lead, latching onto Phillipe Coutinho's through ball and firing low into the corner.
Nabil El Zhar pulled a goal back for 14th-placed Leganes in the 68th minute.
Barcelona: Marc-Andre Ter Stegen 6 (out of 10), Nelson Semedo 6, Gerard Pique 6, Thomas Vermaelen 6, Sergi Roberto 5, Andre Gomes 5, Ivan Rakitic 6, Philippe Countinho 6, Ousmane Dembele 7, Luis Suarez 6, Lionel Messi 9.
However, the French forward is growing with confidence in each passing game since the turn of the year and is finally settling down at the Catalonian club.
Barca to win to nil is priced at 8/15 (1.53), although more appealing is the price of 9/10 (1.90) for Valverde's side to win with a -2 handicap.
"When you start to feel like you are the champions, that's the moment you begin to make a mistake", he said. "We have to keep fighting until the end, just like our other rivals".
After netting their second, the hosts elected to afford Los Legionarios a breather and wound down in the closing minutes of the opening 45 before referee Burgos Bengoetxea called time with Blaugrana taking a two-goal advantage into the break.
Betis temporarily at least, moved into fifth place with a 2-0 home victory over Eibar thanks to Sergio Leon's 11th goal of the season and an own goal from Anaitz Arbilla.