Ferrari drivers Charles Leclerc and Sebastian Vettel are unsure they will be able to compete with Mercedes' long-run ಌpace in Sunday's United States Grand Prix after a difficult Friday of practice running at the Circuit of The Americas.

Leclerc and Vettel finished P2 and P4 respectively in second p♎ractice at COTA on Friday as Lewis Hamilton headed the timesheets for Mercedes, sitting three-tenths of a second clear of the field.

While Leclerc was pleased with how his qualifying pace had stacked up compared to his rivals, he was less c🀅onfident about his long runs, with aꦛverages showing Ferrari to be trailing both Mercedes and Red Bull.

"I think it was a positive day, especially fo⛎r the qualy pace. I think we were strong tod💙ay," Leclerc said.

"In FP1 I couldn’t show the real potential, the lap time was deleted and a few things like this, then we h𒁃ad a problem. Overall I think it has been a positive day.

"The race run though is not as positive as the qualy ꦕruns, and Lewis seems very strong on that."

Asked if he could take the fight to Mercedes 𓄧at COTA, Leclerc replied: "In qualifying, I think so.

"In the race, we’ll🅘 see. It might be a bit harder."

Vettel echoed his recent comments about Ferrari's one-lap p🍷erformance masking its deficiencies in race pace, the team having claimed each of the last six pole positions.

"[Friday was] good to start with, that was po𓃲sღitive, but then we missed a bit. We tried some things and it didn’t really pay off," Vettel said.

"I thinꦚk we have a good understanding, hopefully tomorrow we can improve. One-lap we should be there or thereabouts, in race trim🧜 we have some work to do.

"In qualy trim we can masks the weaknesses a bit, whereas iᩚᩚᩚᩚᩚᩚ⁤⁤⁤⁤ᩚ⁤⁤⁤⁤ᩚ⁤⁤⁤⁤ᩚ𒀱ᩚᩚᩚn the race we struggle, and we can’t. But let’s see.

"I’m quite confident that we can improve the car, that’s what’s m𝓡ost important and what we need to focus on, and then we see what 🙈we get."