Formula 1 power unit providers are braced for a challenge in Mexico this weekend due to the altitude of the Autodromo Hermanos Rodriguez in Mexico City.
The circuit, which returns after a 23-year absence, sits 2,200 metres above sea level, the highest venue on the Formula 1 calendar, three times higher than Interlagos.
With only around 78% of the Oxygen present at sea level, the turbo charger must work harder to deliver the same power output, while cooling will also be an issue.
"Top speeds will be amongst the highest of the season - despite more downforce being required than at Monza, for example," explained Mercedes' Paddy Lowe.
"This is aided by the altitude of Mexico City which, at over 2,000 metres, reduces drag effect.
"The rarefied air density will all make cooling a challenge, and also means the turbocharger compressor must work harder in order to deliver equivalent power output to sea level."