Spain's two biggest clubs breezed through fourth-round encounters against lower league opposition this week using largely second-string line-ups, but will have to dust off their biggest stars should they meet in the last eight.
Friday's fifth-round draw pitted reigning champions Madrid against Malaga, while last year's beaten finalists Barca will play Osasuna.
Elsewhere, there is an eye-catching encounter between Valencia and Sevilla, Real Sociedad meet Real Mallorca and Espanyol face Segunda Division outfit Cordoba.
Second-tier Alcorcon take on Levante, while Racing Santander and Athletic Bilbao face third-tier opposition in the form of Mirandes and Albacete Balompie respectively.
The last-16 ties are played over two legs, with the first match on January 4 and the return on January 11.
The quarter-finals will be held on January 18 and 25, with the semis scheduled for February 1 and 8.
Copa del Rey fifth-round draw:
Mirandes v Racing Santander
Albacete Balompie v Athletic Bilbao
Alcorcon v Levante
Cordoba v Espanyol
Real Sociedad v Real Mallorca
Valencia v Sevilla
Barcelona v Osasuna
Real Madrid v Malaga