Having come on in the first half for the injured Ousmane Dembele to make his 100th Barca appearance, Pedri notched the winner in the 61st minute after Jordi Alba's cross came to the 20-year-old via goalkeeper Paulo Gazzaniga. Xavi's men increase their advantage over second-placed Real Madrid ahead of Los Blancos hosting third-placed Real Sociedad on Sunday. Barca later said Dembele had "strained the rectus femoris muscle in his left thigh."
Richarlison has been limited to only three substitute appearances since the World Cup having been struggling with a hamstring problem.
Warne joined from Sky Bet Championship side Rotherham in September and was given the task of rebuilding the Rams.