The Spaniard finished Q1 in fifth position after setting the quickest time in the middle sector, before deciding against posting a laptime in Q2 to save tyres.

Alonso is to start from the back of the grid after receiving a 20-place grid penalty for an engine change.

The McLaren driver hailed the Mexico weekend as the best for his team so far, but made it clear all the progress was coming from the chassis and not from the Honda engine.

"The engine is the same," he said. "In fact, today we have the previous engine. Yesterday we used the new engine but saved it for Brazil and Abu Dhabi.

"So all the improvements are thanks to the aero and a bit to the suspension parts we've brought over the past races. As of today, or at least today, we have the best car."

Alonso, who outpaced teammate Stoffel Vandoorne by eight tenths of a second in Q1, still reckons it will be very hard to score points in the race given his starting position and the long straight of the Mexican circuit.

"The car was handling incredible," he added. "In the corners it has very good grip and it allows you to drive instinctively and easily. A spectacular weekend up until now.

"It's been a while since we set a pink sector. It's probably the best weekend of the whole season.

"Unfortunately with the engine penalty we start last, so tomorrow will be almost impossible to score points because on the straight we won't be able to overtake, but we are preparing 2018 as best as possible.

"Today, for the first time in three years, we can be pretty sure that we had the best car on track."