Mariano plundered a hat trick and Enzo Zidane scored on his senior debut as Real Madrid swept aside Cultural Leonesa 6-1 to cruise into the last 16 of the Copa del Rey with a 13-2 aggregate victory.
With one eye on Saturday's El Clasico at Barcelona and given their healthy 7-1 lead from the first leg, it was no surprise to see Real Madrid coach Zinedine Zidane make sweeping changes against the Segunda Division B side.
Starlets Tejero and Martin Odegaard both started, while James Rodriguez also came into the team and there was a welcome return for Brazilian midfielder Casemiro, who had been out since mid-September because of a fractured leg, with 21-year-old Enzo on the bench.
There was a minute's silence before kick off at the Santiago Bernabeu in memory of the victims of the plane crash in Colombia which killed 71 people and most of the Chapecoense football team from Brazil.
When the action started, it took the La Liga leaders just 22 seconds to put the ball into the Leonesa net.
Marco Asensio robbed Leonesa captain Ivan Garrido on the right side of the penalty area before cutting the ball back for Mariano to sweep home.
Mariano saw another close-range effort ruled out for offside before Real Madrid made it 2-0 on 23 minutes when Rodriguez headed in a cross from Daniel Carvajal at the near post.
Dominican Republic forward Mariano did get his second three minutes before half-time with a fine finish as he chested down a curling ball into the area and sent an angled drive past goalkeeper Leandro.
Leonesa, though, grabbed themselves a memorable consolation goal on the stroke of half-time when midfielder Yeray lashed the ball past Kiko Casilla when it dropped to him on the edge of the Real penalty area.
Zidane sent his son Enzo on for the second half to replace Isco and make his official debut, the youngster having appeared for Los Blancos during their preseason build-up.
Danish teenager Odegaard fired wide before 21-year-old French midfielder Enzo added a fourth in the 63rd minute when he drilled in a low shot following some neat interplay around the edge of the penalty area.
With the result beyond doubt, Zidane made more changes, including a first-team debut for goalkeeper Ruben Yanez, before Tejero's angled drive hit the base of the post.
Mariano completed his hat trick on 87 minutes with a close-range header and defender Cesar Morgado then diverted a low cross into his own net to complete the rout.