Endrick (right) helped Real Madrid bounce back from the 5-2 defeat by Barcelona in the Spanish Super Cup final
Real Madrid needed extra time to defeat Celta Vigo and book a place in the quarter-finals of the Copa del Rey.
With the game ending 2-2 after 90 minutes, Brazilian Endrick scored twice in the second half of the extra period to send Carlo Ancelotti's side through.
In a battling comeback from 2-0 down, Celta struck a 91st-minute equaliser from former Chelsea defender Marcos Alonso to keep the last-16 tie alive.
Real looked in command with goals from Kylian Mbappe and Vinicius Jr, but endured a nervy finish when Jonathan Bamba pulled a goal back for the visitors in the 83rd minute.
Claudio Giraldez's side levelled when Alonso, who came through the youth ranks at Real Madrid, scored from the penalty spot after Bamba was fouled in stoppage time.
However, Endrick came off the bench to put Real back in front, before a Federico Valverde strike made it 4-2. The 18-year-old Endrick's clever backheeled finish sealed the success at Santiago Bernabeu.
Elsewhere on Thursday, Spanish Cup holders Athletic Bilbao were upset 3-2 by Osasuna.
Ante Budimir starred for visitors with a double, adding to Aimar Oroz's opener, as goals from Nico Williams and Oscar de Marcos for Ernesto Valverde's hosts proved in vain.
Last season's semi-finalists Real Sociedad also booked a spot in the last eight after a 3-1 home win against Rayo Vallecano.
The draw for the quarter-finals will take place on Monday, 20 January, and will also feature Barcelona, Atletico Madrid, Valencia, Leganes and Getafe.
