Valtteri Bottas blames brakes for Austin qualifying troubles

Carpooling with Valtteri Bottas (4:40)

Laurence Edmondson joins Valtteri Bottas on his journey to the Circuit of the Americas and discusses his career, his future and his relationship with team mate Lewis Hamilton. (4:40)

Valtteri Bottas believes the 0.478s gap to Mercedes teammate and polesitter Lewis Hamilton was mainly down to struggles in the final sector of the lap.

Since the summer break, Bottas has been consistently out-performed by champion-elect Hamilton and Saturday was no different. The Finn looked solid throughout Q1 and Q2, but faltered when it mattered as he failed to extract the maximum from his Mercedes in Q3 -- ending qualifying in third, behind Hamilton and Ferrari's Sebastian Vettel.

"Definitely the last sector in the qualifying, I did struggle more,'' Bottas said. "It felt more tricky, for some reason than in some of the practice sessions. There have been things I have been struggling with this car, brake modulation and front locking, transferring weight between the wheels, it's fine details.

"I have struggled to get it together and many times [Turns] 13 and 15 I lost a bit of time -- sometimes I got it right, still didn't manage.''

Bottas was left without answers when asked what happened in Q3, as both Hamilton and Vettel found pace, Bottas struggled to find improvements on an improving circuit.

"I couldn't improve in the second run. The first run felt okay. Lewis managed to gain, somehow, more from Q2 to Q3, I couldn't find any track improvements I couldn't improve in the second run.

"Like I said, It was not easy sessions, every lap was always a bit different. There was no big mistake, more things here and there, there was just this big gap.''