SPA-FRANCORCHAMPS, Belgium -- In the early 1980s, NASCAR legend Dale Earnhardt was given the nickname One Tough Customer. The nickname, which was also the advertising strapline of his sponsor Wrangler Jeans, stemmed from his reputation as one of the most intimidating drivers in the circuit.
On Sunday evening, Red Bull team principal Christian Horner described Max Verstappen using exactly the same words. The only difference was that it had nothing to do with the way he raced against his rivals at the Belgian Grand Prix, instead it was about the back-and-forth he was having with his race engineer, Gianpiero Lambiase.
"I think to race engineer Max Verstappen, you've got to have strength of character, because he is one tough customer," Horner told reporters after Verstappen's eighth consecutive victory and his 10th of the season.
"Many race engineers would crumble under that pressure, and GP [Gianpiero] has got the strength of character to deal with that, and the respect and trust is there between both the guys."
An hour or so earlier, the exchanges between Verstappen and Lambiase had provided some much-needed entertainment in an otherwise processional race. At times it sounded like a genuine disagreement between the two, but Lambiase stood his ground -- as he had done during a series of terse radio communications during qualifying on Friday.
"So don't forget Max, use your head, please," Lambiase warned Verstappen as the first round of pit stops got underway.
Verstappen, wanting to know why his teammate Sergio Perez pitted first, responded: "Are we both doing it or what?"
Lambiase replied: "You just follow my instruction."
Verstappen hit back: "No, I want to know [if] both cars do it."
Lambiase cut him off: "Max, please follow my instruction and trust it, thank you."
Later in the race, Lambiase warned Verstappen against taking too much life out of his tyres as his driver started to chase fastest laps.
"You used a lot of tyre on the out lap, Max," he said. "Not sure that was sensible."
Lambiase added: "This tyre had reasonable degradation in the first stint. I'd ask you to use your head a bit more."
Verstappen joked in response that he could, if he wanted to, build a big enough lead to change tyres again and use the fresh rubber to secure the fastest lap.
"I could also push on and we do another stop?" he said. "A little bit of pit stop training [for the mechanics]."
Asked in a postrace news conference if he had been joking around in the messages or was being serious, Verstappen said: "Probably 50/50 in the messages. I know that the team doesn't like to do another stop, but I like to mention it so they might get a bit nervous.
"I like the response of, 'No, no, we are not doing that today.' It's fine. We know each other very well and we have a very good relationship."
Verstappen's 10 victories this season, eight of which have come at the last eight races, means he is well on his way to a third title in a row. Horner believes Verstappen's relationship with Lambiase, and their ability to be forthright with one another, is key to their success.
"GP and Max have been together since the first race that Max stepped into a Red Bull car," he said. "Max is a demanding customer. You've got to be a strong character to deal with that; GP, he's our Jason Statham equivalent, or certainly look-alike.
"He deals with him firmly but fairly, and there's a great respect between the two of them. And that comes out of a mutual trust that you must have with an engineer. The conversation between the two of them, there's 200 million people listening to them. There's a great bond between the two and a great trust between the two."
Despite Lambiase's pleas for Verstappen to take it easy, the championship leader still won Sunday's race by 22 seconds from Perez. Horner said he had some concerns about Verstappen pushing too hard, but was reassured by Lambiase's reading of the data.
"What you have to remember is the engineers and the performance engineers, they're living and breathing all the data they have in front of them, they can see, and they know their drivers' driving style, they know what they're taking out of the car and so on.
"I was asking GP, 'I know what he's doing here, he's trying to build a gap up for a pit stop,' and GP said, 'Look, I think he's taking it pretty easy, the metrics are massively under control.'
"So it's having that trust and bond that's so important, which is what those two guys have.
"Sometimes it gets a bit sparky between the two of them. But Max is the kind of character that will rev very quickly and it'll come down very quickly. GP doesn't forget so quickly."