Williams is continuing to fight uphill battles this weekend in Las Vegas as a knock-on effect from accidents and retirements in Mexico and Brazil leaving them struggling to catch up.
Damage to both cars in recent outings had left the squad scrambling to get two cars ready for Alex Albon and Franco Colapinto to drive in this week's race.
While Colapinto put in 29 laps in Thursday's second practice, his team mate Alex Albon was less fortunate, suffering fuel system problems early in the session that left him pulling over to the side of the track and triggering a red flag.
"After the damage we suffered in Mexico and Brazil, the team did a phenomenal job to get us ready for this weekend," said sporting director Sven Smeets after the end of practice. "Every lap counts on this tricky circuit.
"Unfortunately Alex suffered a fuel system issue which has put us a bit on the back foot," he acknowledged after Albon completed just four laps in the second session.
"We’re certainly lacking mileage today," conceded Albon. "Around this track, getting those laps in is vital as it’s so tricky and you need to feel confident with everything, especially your braking confidence.
"We’ll be able to fix the issue [overnight] but we certainly have a lot of work to do tomorrow in FP3," he continued.
"We need to look at our performance and see where we can improve but it will be about getting those tyres in the right window," he said when asked about the team's plans for tomorrow. "We’re not quite there yet."
Williams team principal James Vowles said that the fuel system issue on Albon's car was "contained" but admitted: “My bigger worry is that you need every lap really around here.
"When you’re limited in the amount of learning you have, especially with just one car - Franco still getting up to speed on the circuit - it puts you on the back foot. That’s my biggest concern.”
Williams has dropped to ninth place in the constructors championship standings over recent weeks, and Vowles admitted that the prospects for improving their position in the three remaining races aren't looking great.
Alpine’s upset double podium in Sao Paulo pretty much ensures that Williams will end the season in penultimate position in the championship with RB now 27 points ahead. But Vowles insisted the fighting spirit was still very much alive.
“I’d say that’s built into Williams,” he said. “And that’s just that’s the heritage that comes with a team that’s won nine World Championships.
"That’s still got that fighting spirit underneath it. I think more than any other time, we can see the pathway that we’re pulling ourselves out of where we were and going towards where we are at the moment.”
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