Espanyol held by Rayo, misses chance of joining Liga leaders
Espanyol led 2-1 at halftime but was pegged back early in the second half at Vallecas Stadium. An injury-time penalty for Espanyol was reversed after a video review showed the foul was outside the area.
Espanyol is two points behind the league leaders ahead of this weekend's matches.
Barcelona hosts Athletic Bilbao on Saturday, while Real Madrid later hosts Atletico Madrid in the first derby of the season.
Striker Raul de Tomas put Rayo ahead early on, but the visitors rallied with goals by striker Borja Iglesias and midfielder Esteban Granero. Gael Kakuta equalized for Rayo with a penalty shortly after halftime.