Carlos Sainz says he is concerned his Mexican Grand Prix could be a long one if he cannot escape cars behind in the DRS zone, suggesting he could be a 'sitting duck' in the Toro Rosso.

Though the Renault-powered cars have performed better than expected around the Autodromo Hermanos Rodriguez since its comparatively poor top speed is being negated by strengths through the twisty infield, the race is expected to be a tougher prospect.

Indeed, Sainz - who starts 11th - is concerned that if he cannot get away from the cars behind before DRS is activated, he will be at a substantial disadvantage down the 1.2km home straight,

"Hopefully we have enough margin from the guys behind getting to that second margin because if not, and they have that DRS and we don't, then they'll have 25-30kph more than us; this is when you're a sitting duck.

"We just need to make sure we keep them out of the DRS, and then we need to make sure we keep on the DRS of others and maybe if they do make a mistake, then we can overtake them. The only problem is obviously it is so tight and so difficult to have a reference in front, that if you're very close behind in the tight section, it will not be easy to overtake for me."