Serbia and Kazakhstan will therefore decide on the decisive double - as has already been the case for the first two quarter-finals.
He must pit Djokovic and Nikola Cacic, on the Serbian side, against Andrey Golubev and Aleksandr Nedovyesov on the Kazakh side.
The winning country will face Croatia for a place in the final.
Without the right to make mistakes, Djokovic quietly held his position against Bublik: a break in each round was enough for the world No. 1, himself never broken and winner in just over an hour and a quarter on a final serve winner.
Serbian Novak Djokovic serves against Kazakh Alexander Bublik in the second single of their Davis Cup quarter-final on December 1, 2021 in Madrid OSCAR DEL POZO AFP
"We have not finished the work, I hope we will win the double", tempered "Nole".
Previously, Mikhail Kukushkin, 182nd in the world, but who was still in the Top 40 at the start of 2019, had won a marathon match - 3h18 min, the longest of this Davis Cup so far - at the expense of Miomir Kecmanovic (69th) 7-6 (7-5), 6-4, 7-6 (13/11) to bring the first point to Kazakhstan.
The joy of the Kazakh Mikhail Kukushkin, after beating the Serbian Miomir Kecmanovic, 7-6 (7-5), 6-4, 7-6 (13/11), and offered the 1st point to his country, during their quarter Davis Cup final, December 1, 2021 in Madrid OSCAR DEL POZO AFP
Kecmanovic, first led by a set and 4 games to 2, had found the resources to revive and get four match points, before giving in.
Croatia and Germany are the first two nations to qualify for the semi-finals.
The last quarter-final will pit Daniil Medvedev's Russia against the Ymer brothers' Sweden on Thursday.
© 2021 AFP