A lack of dry running on Friday, and perhaps on Saturday, would likely lead to a "lottery" on race day, according to Red Bull's Daniel Ricciardo.
Teams and drivers braved the elements on Friday, although the day's second free practice saw track-activity take place only in the closing stages of the session.
Forecasts are calling for another wet day of running at the Circuit of the Americas on Saturday, leaving drivers unprepared for what should be a dry Sunday.
"For sure the wet is exciting to drive in and it could change things up tomorrow, but if it’s dry I think we also have a pretty good car, so I don’t really mind what happens in qualifying," said the Aussie.
"The race could be a bit more of a lottery if it’s the first dry running we get."
Friday's sessions - and especially FP2 - saw relatively limited running, with teams purposefully limiting their use of wet tyres given the prospect of more rain on Saturday.
"We would obviously have liked to run a bit more but I a puncture in my first set of Intermediates this morning so we couldn’t use that set again," added Ricciardo.
"If we had used another set in FP2 that could have taken a set away from us tomorrow in qualifying, which is obviously more important than running this afternoon.
"If we had more tyres available, we would have seen more running.
"Fortunately, this morning we got a few laps in and understood a bit about the car in these conditions and we definitely felt an improvement from Monza."
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