Red Bull team boss Christian Horner has explained that Max Verstappen's car was called back to the pits during first practice in Miami amid temperature concerns.
The F1 paddock was greeted with hot conditions for Friday's opening session at the Miami International Autodrome, with air temperatures above 30 degrees Celcius, and track temperatures in the mid-40s.
After some exploratory runs, which included a brush with the wall, Red Bull brought Verstappen back to the pits, where mechanics removed bodywork and huddled around the rear of his RB18.
Early gremlins for Verstappen and Red Bull
Speaking during the session, Horner offered an explanation for the stoppage.
"The car was just running a little bit hot on Max's side of the garage, so they're just investigating why," Horner told Sky Sports F1.
"We've got a bit of debris in the corner or something, so that's why that car's in for a bit of maintenance."
With television footage showing engineering chief Paul Monaghan and design chief Adrian Newey in attendance, Horner added: "You can see them looking at the cooler there, so [they're] just wanting to make sure we get the temperatures under control at this stage.
"You don't want things running hot and cooking themselves."
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How will the Red Bull/Ferrari battle unfold?
Ferrari's Charles Leclerc topped the first practice session, finishing a tenth clear of Mercedes driver George Russell, followed by the Red Bulls of Verstappen and Sergio Perez.
Given the all-new challenge of the Miami venue, which mixes tight, twisty sections with several long straights, Horner is intrigued to see how the pecking order shapes up from here.
"We've gone for the best set-up that we think... that our simulators have told us for this circuit," Horner commented.
"Ferrari have dropped the wing level. We've seen in Jeddah, where we were actually quicker on the straight, but in the slower stuff, the medium speed, Ferrari were quicker, so that wing worked for them in that area.
"It's going to be fascinating to see how the wing levels work here and whether we want to go up or down further for the next session."
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