George Russell topped the time sheet in FP1 around Miami, leading his teammate Lewis Hamilton and Ferrari’s Charles Leclerc, as Red Bull underperformed during the session.
Max Verstappen only managed P4 in the end, even after showing strong promise in the opening stages of FP1.
After a red flag incident caused by Nico Hulkenberg’s crash, Red Bull and Mercedes took different approaches to their data collection efforts ahead of Sunday’s Grand Prix.
“It’s new asphalt, so then you slide more – we knew that,” Marko said, explaining Red Bull’s poor pace.
“Over the weekend, that will get better. The track evolution will be important here.
“That had to do with the fact that when Mercedes were doing fast laps, we were doing long runs.
“They also used more power. I believe our set-up for the long run was very good again, because it looked okay for us as well.”
Perez-Verstappen battle escalates in Miami
Red Bull are looking to continue their dominant streak in Miami, having scooped victory in every race of the season so far.
Verstappen took P1 in Bahrain and Melbourne, while Sergio Perez secured victory in Saudi Arabia and Azerbaijan, as well as the Sprint race in Baku.
The two Red Bull drivers are locked in a tight battle for the Drivers’ Championship, with Verstappen holding a six point lead over Perez.
With Miami essentially being street circuit, Perez has a chance at taking the lead in the Drivers’ Standings for the first time in his career, as the track plays to his skill set.
In the Constructors’ race, Red Bull has secured a runaway lead with just four rounds completed, building up an almost 100 point lead over their nearest rivals Aston Martin.