Real Madrid suffered their second defeat of the week and slipped to third place in La Liga after losing 2-1 at Sevilla.
Ronaldo put the visitors ahead after fourteen minutes but two goals from Bacca, one in each half, gave Sevilla the three points.
Barcelona were comfortable 3-0 winners over Celta de Vigo, Neymar scoring twice and Messi getting one to see Barcelona move up to second place in La Liga, one point adrift of the leaders. Barca goalkeeper Victor Valdes suffered a serious injury early in the match which looks likely to keep him out of the World Cup.
Atlético Madrid overcame Granada 1-0 with a second half strike from, almost inevitably, Diego Costa and they lead the way by one point with eight matches remaining.