Leclerc has clearly been ahead of Sainz in Austin, having taken pole for Sunday’s main race and qualified second in the Saturday shootout, while Sainz was fourth and sixth in the two sessions.
Sainz says that the sprint weekend meant that he couldn’t optimise the car over the bumps, which are more severe this year, in FP1.
"For me it's mainly track characteristics,” said the Spaniard when asked about Leclerc’s advantage.
“The car here is bouncing around a lot and jumping around a lot and when that's the case normally Charles copes with it a bit better than I do.
“And this time I didn't have time to change the setup to improve it, to put it a bit more to my liking, and go into the race weekend a bit more comfortable with the car to extract more and more performance.
“In sprint weekends that's the problem, that you're stuck with the baseline set up more or less that you can run and the amount of bumps again this year surprised us being even bumpier than last year. I'm just not coping very well with it in the high speed. Not a lot of confidence.
“I feel like the car is going to snap on me at any point in time, and I'm having to drive one step under the limit, which is never ideal in quali."
Sainz was the only driver in the field to opt for soft tyres for Saturday’s sprint, and from sixth on the grid he gained two places.
He subsequently fell back behind Lando Norris and Sergio Perez to finish in the position in which he started, having successfully fended off George Russell.
“First of all on the grid being the only one on softs doesn't give you a lot of confidence,” he said of his choice. “We thought there were going to be more cars out there with softs.
"If we go for soft it means that our tyre model suggests that it's not a bad tyre to go on. If not, we simply wouldn't even consider it. It suggested that it could be a decent tyre for this race, as previous years the soft has been a decent tyre here.
“This time around clearly we need to analyse if we can do something, because was it worth the risk? And maybe it wasn't. But we need to analyse how we can maybe do a bit better there. In the end it paid off at the start, but at one point it did look like it was going to be very tricky."
Sainz admitted that he was surprised to be able to hang onto sixth position.
“Mid-race once Lando and Perez passed me and George was attacking me I thought we were just going to go backwards,” he said.
“I managed to recover the tyre well, and did some good defending in order to keep them behind. And we brought home a P6 that at one point didn't look like it was going to be possible.
“Unfortunately, for me, it's been more defending than attacking all year long! But probably because of doing so much defending all year I'm getting some practice, and I'm getting better at it."
Asked if he’d questioned the soft tyre strategy call, he said: "I'm going to keep that for myself! But obviously it was a tough call to do.
“But in the end also we learned some valuable information for my team, given tomorrow there's plenty of strategies available out there, and now we know how the soft behaves we can map it, and compare it to the medium."
