An uneventful opening 45 minutes failed to produce a clear chance for either side as Madrid struggled for invention against the Segunda B side.
The away side improved in the second half, but could not make the breakthrough as Olimpic held on for a famous draw against Los Blancos.
Read how the first leg unfolded in Sports Mole's minute-by-minute live commentary of the action below.
OLIMPIC: Francis; Pepin, Vicente, Kike, Peris; Belda, Samu, Jordi, Rifaterra; Mosquera, Perales
REAL MADRID: Casillas; Carvajal, Nacho, Ramos, Arbeloa; Illarramendi, Casemiro; Di Maria, Isco, Jese; Morata
COPA DEL REY HALF-TIMES: Huelva 0-0 Levante, Olimpic 0-0 Real Madrid