AUSTIN, Texas, Oct 25 - George Russell was searching for answers after finishing eighth in a US Grand Prix won by Formula One champion-in-waiting Mercedes teammate Kimi Antonelli on Sunday.

The Briton started in sixth place on the grid at Austin's Circuit of the Americas, collected a five-second penalty for an incident with McLaren's Oscar Piastri and said he had no explanation for his lack of pace other than "just not being quick enough."

“I need to try and understand why it is. It’s strange when you’re so far off, so hopefully there’s some answers somewhere. But, anyway, I don’t have one,” he told Sky Sports television.

The result left Antonelli on the brink of a coronation, the title surely his for the taking in Mexico next weekend with Russell still his closest rival but now 123 points behind and with a maximum 125 to be won.

“The pace wasn't good on the first stint," Russell told reporters. “But when I came out of the pits on the hard (tyres), I probably did six laps where I was lapping the same pace as Kimi. But then I caught up with Oscar and I just couldn't overtake.

"Six good laps, 50 bad laps. I want to understand why the pace was so bad on the first stint."

Team boss Toto Wolff said Russell had just struggled.

"George for all of us in the team is a champion and has won in every category and I think he merits to be put in the group of the very best ones. And we've seen that last year," said the Austrian.

"This year ... we see this variability in results. When we land the car in a way that suits him, he's absolutely fast. But when it drops out of that operational window, he struggles. And he struggles more than maybe Kimi.

"We just have to work it out with him, how there can be such a difference in driving, in performance. Because George is not half a second slower, three tenths slower than Kimi. That's just absolutely not the case." REUTERS