With Vettel nursing a 13-point lead, the title fight boils down to this: he will be champion if he finishes in the top four, even if Alonso wins; if he finishes fifth, sixth or seventh if Alonso doesn't win; if he finishes eighth or ninth if Alonso finishes third or lower; or if he finishes 10th or worse and Alonso isn't on the podium.
Alonso will be champion if he wins and Vettel is fifth or lower; if he is second and Vettel is eighth or lower; or if he is third and Vettel is 10th or lower.
Yesterday's two practice sessions suggested that there is not a lot to choose between either driver's machinery, as they were both within half a second of pacesetter Lewis Hamilton.
"Weather-wise, it's Sao Paulo," Vettel said. "It's the same as if you go to Spa (home of the Belgian Grand Prix), things can happen quickly and the weather can change a lot here.
"Probably there's some rain on the way, but then again you don't know how much and when." (© Independent News Service)