Charles Leclerc admits he had no idea that Ferrari had the potential to take pole position even starting Q3 at the Mexico City Grand Prix. Success on Saturday in Mexico makes it two pole positions in a row for Leclerc who was also fastest in Austin last weekend, although he faded in the race to finish sixth before a post-race disqualification. On that occasion, Leclerc had looked quick from early in the session but Ferrari’s Q3 pace at the Autodromo Hermanos Rodriguez came as a surprise. “It’s a really big surprise but we keep saying that every time we get…