Spanish champions Barcelona will face third-division side Unionistas de Salamanca in the Copa del Rey round of 16, while holders Real Madrid travel to Atlético Madrid for a second meeting with their crosstown rivals in the span of seven days.

Unionistas beat LaLiga side Villarreal on penalties to progress to this stage and are the only third-tier team remaining in the competition.

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The game had kicked off on Sunday, but floodlight failure halted the tie at 1-1 in extra time, with the match played to a resolution on Monday before the draw.

Barça, meanwhile, had to work hard to overcome fourth-division side Barbastro on Sunday, eventually securing a 3-2 win with goals from Fermín López, Raphinha and Robert Lewandowski.

Tenerife are the only other non-LaLiga side left in the competition, and the Segunda División side were drawn at home against Mallorca.

The other six ties are all LaLiga affairs, with Madrid facing a difficult trip across the city to take on Atlético at the Metropolitano.

The ties will be played next week, spread across Jan. 16, 17 and 18, but there will be a meeting between Madrid and Atlético before then, with the two teams facing off in Saudi Arabia on Wednesday in the Spanish Super Cup semifinal.

The winners will meet either Barcelona or Osasuna, who play on Thursday, in Sunday's final.

Elsewhere, in the Copa del Rey, surprise LaLiga leaders Girona will host Rayo Vallecano, while 23-time winners of the competition Athletic Club are at home to Alavés.

Only Barça have won the Copa more times than Athletic, securing the trophy for the 31st time in 2021, while Madrid's success over Osasuna in the final last year won them the title for the 20th time.

Full draw: Unionistas de Salamanca vs. Barcelona, Tenerife vs. Mallorca, Getafe vs. Sevilla, Osasuna vs. Real Sociedad, Valencia vs. Celta Vigo, Athletic Club vs. Alavés, Atlético Madrid vs. Real Madrid, Girona vs. Rayo Vallecano.