Christian Stuani's third-minute opener has been cancelled out by an Iago Falque equaliser as Espanyol and Rayo Vallecano go into the break with the scores level at 1-1.
Stuani slotted home after Pizzi had accelerated past Ze Castro down the right wing and centred for the midfielder in the early stages of the game.
The visitors almost hit back within a couple of minutes, but Kiko Casilla was happy to see Joaquin Larrivey's looping header drop onto the roof of the net.
Midway through the half, Sergio Garcia was bundled over clumsily by Ze Castro, but the referee waved away the protests of the home support.
With half time approaching, the visitors got back on level terms. Alberto Bueno pounced on a slip by David Lopez and fed Falque, who coolly placed the ball into the top corner to make it 1-1.
