Max Verstappen has conceded his United States Grand Prix victory was made "tougher" by a persistent brake issue at the Circuit of the Americas.
The Dutchman came under a late attack from Mercedes' Lewis Hamilton but had just enough of a gap in reserve to take his 50th F1 race win - his 15th of the season.
Verstappen had started from sixth on the grid after exceeding track limits on his best qualifying effort on Friday but expertly nursed his Red Bull to the front as tyre management and pit stop strategy reigned supreme.
But his temper over team radio flared on a number of occasions as he bemoaned issues with his RB19 and explaining the complications, Verstappen said: "The whole race, I was struggling a lot with the brakes.
"There are quite a lot of braking points around here and I couldn't really get the same feeling as yesterday, so that made it a bit tougher.
"But you could see it was very close at the end and also, with the backmarkers and the tyres going, it makes it a bit more difficult."
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Verstappen didn't take the lead until the midway point of the race and asked why he wasn't able to scythe straight to the front, he replied: "You don't want to destroy the tyres but at the same time, I was struggling a lot on the braking.
"So it took me quite a while to find a middle."
On joining the 50 wins club, Verstappen added: "It is incredible to win my 50th Grand Prix here. I am very proud, of course, and we will keep on trying to push for more."