Madrid host neighbours and LaLiga leaders Atletico at Estadio Alfredo Di Stefano with Diego Simeone's men holding a one-point advantage over Real Sociedad at the top of the table.
The defending champions are five points further back having already lost three games in 2020-21.
Key to Atletico's unbeaten start has been the form of Llorente, who has four goals and two assists in the league. He has featured in every game, making six starts.
Llorente also scored a goal and registered an assist as Atletico came through the Champions League group stage and enjoyed an impressive performance against Barcelona in their 1-0 win over the Blaugrana last month.
He completed 90 per cent of his passes in the Barca half, only Koke (93.3) and Angel Correa (95) fared better among Atletico players to attempt more than one pass in the opposition half. Llorente was also one of four players to record two interceptions.
Sold to Atletico by Madrid in June last year, all signs point to Llorente having a significant role to play if Atletico are to claim a crucial win this weekend, with Zidane believing they are harnessing talent the midfielder has always had.
"He is not surprising me. He is a high-level player and he is showing another facet that he did not have at Madrid," Zidane told a media conference.
"It was known that he had a lot of quality and I am happy for him, nothing more."
Two Madrid players who may have to play the role of spectators in the derby are Marcelo and Isco.
Marcelo has made only five starts in LaLiga this season and has not featured in the Champions League since Madrid's opening group game.
Just three of Isco's eight league appearances have been starts and he has played only one game in the Champions League.
Neither featured in Wednesday's win over Borussia Monchengladbach that secured their place in the last 16.
Zidane said of that duo: "I will always have confidence and I will count on them.
"They have always shown everything they have done here. It is true that they have not played in the last games, but I have to choose, it is my job. I will count on them."
Asked about player fatigue amid this season's congested schedule, Zidane replied: "Each game is different and has its history.
"It is true that we have not made many changes in these two games, but it is a particular moment.
"Tomorrow there is another game and there may be five changes, maybe not. It depends on each game."