The Spaniard had an underwhelming Mexican Grand Prix last weekend, finishing in P13 after qualifying seventh and even going up to sixth after the start of the race. The race pace however, particularly on the hard compound after the first stop, was subpar on the 25-year-old's MCL34.
He got picked off left and right by midfield contenders and finished outside the points, with teammate Lando Norris retiring as well after losing two minutes in a nightmare pitstop.
On Friday at COTA, Sainz used most of FP1 to test out the new 2020 compound, which was made available to all teams to test.
“It’s been a bit of a different Friday, having next season’s tyre compounds available," the man from Madrid said.
"Unfortunately, my first impression of these tyres wasn’t very positive."
He wasn't much happier once he got back on this year's tyres, however, with the tricky conditions at COTA making it more difficult to extract the maximum from the car.
"I felt we were probably struggling a bit more this weekend to find the right balance in the car," he continued.
“It took us a few more runs to find a better compromise, but by the end of the day, we more or less managed to find a decent baseline. However, this weekend looks extremely tight and I expect a tense fight to get into the top 10."
Sainz has dropped back to P7 in the midfield battle, with Pierre Gasly taking his place back following an impressive showing in Mexico. McLaren still lead the midfield with relative comfort, however, as the gap between them and Renault being 38 points with three races to go.