BAKU, Azerbaijan -- Red Bull team principal Christian Horner has explained the timing of the pit stop that saw Max Verstappen lose the lead of the Azerbaijan Grand Prix and fall behind teammate Sergio Perez.
Verstappen took the lead of the race on Lap 4 from Ferrari's Charles Leclerc, who started on pole position, and was ahead of Perez in second place when he was called into the pits on Lap 10. However, a safety car period immediately after Verstappen's stop saw Perez lose less time when he made his tyre change and, along with Leclerc, emerge ahead of Verstappen before the race restart.
The safety car came out when AlphaTauri driver Nyck de Vries hit the inside barrier at Turn 5 and then went straight on at Turn 6 shortly before Red Bull called Verstappen into the pits. The tap against the barrier broke the steering on De Vries' car and resulted in him being unable to continue, leading to a safety car to allow the marshals to clear the AlphaTauri.
"The unfortunate thing was the safety car, with 20/20 hindsight you'd have left him out there another lap," Horner said of Verstappen's pit stop. "At the time from what we could see, we decided to pit Max because he was starting to struggle a little bit with the rear tyres on his car, and Checo was obviously right up behind him.
"So we decided, from a strategy point of view, it was the optimum time to take the stop. And with De Vries, the glimpse that we got, all four wheels were on the car, he hadn't hit the barrier. And the engine was running.
"It looked like he would select reverse and carry on. We never expected that to go to a safety car.
"Obviously with 20/20 vision, we'd have just done one more lap and gone from there. You just don't know at that point whether Charles is going to pit and then he suddenly jumps both of them."
Footage of De Vries' crashed car from above showed one of the front wheels facing the wrong way, but Horner said his team simply didn't register the damage.
"The problem was we didn't have the visibility of De Vries, it was a quick shot of him and just a black set of lines, looked like he'd outbraked himself, hadn't hit the barrier," Horner added. "Usually if you see a car in the barrier, it's a safety car, but there was no sign of it having hit the barrier.
"And so yeah, it was only subsequently I think on the replays that you were able to see a track rod was broken."
After the race, Verstappen said it was something the team would review but that the damage to De Vries' car had not been obvious to him either.
"I could see the car stopping, and you could see it on [the trackside] screen, but from the car you can't go into detail to see if all the wheels are connected properly," Verstappen added. "Of course, the team has a bit more of an overview to that, so we will look into that to see if there is anything we could have done different. But I also don't know when the exact call came to pit, so it's a bit difficult to say at the moment."
Horner also praised the performance of Perez, saying he had shown impressive pace before the safety car after he passed Leclerc for second place and closed in on Verstappen in the lead.
"Checo passed Leclerc and he closed the gap down to Max," Horner said. "Yes, he got lucky through a safety car, but as I said earlier, he then had to get on and deliver.
"You've got Max Verstappen behind you, he's not taking it easy. He was able to build up I think a 3.7-second lead at one point. And all credit to Checo, drove a great race today."