If Fernando Alonso has been praying to the weather gods in Brazil, as his prime hope of snatching the world championship from Sebastian Vettel, an 80 percent chance of rain for the race may prove his salvation.
With Vettel nursing a 13-point lead after last weekend's US Grand Prix in Austin, what the title fight boils down to is 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 if 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 within half a second of pacesetter Lewis Hamilton, the interloper who beat them both with his excellent victory for McLaren in Texas.
"Weather-wise, it's Sao Paulo," Vettel said. "It's the same as if you go to Spa, things can happen quickly and the weather can change a lot here. I spoke to some locals and I think there was a big rain two days ago which wasn't expected. Probably for Saturday, Sunday there's some rain on the way, but then again you don't know how much and when. I asked Pirelli yesterday if they have all the containers here with the rain tyres, and that's the case, so I don't think we have to be concerned.
"I think the circuit seemed to suit our car in previous years. We had all eyes on Friday to get into the groove, but I think we can be as confident as we can be in this stage. Obviously we know there is a lot ahead, but we are in a great position."
Alonso has it all to do. "The first priority for us is to be on the podium," he said, "which gives us the possibility to score more than 13 points, and then we need to see with Red Bull because it is not in our hands. We haven't got much to lose, we have only the possibility to win something, and we will try to do our best."
Race for the title: Who needs what
* If Sebastian Vettel wins tomorrow's race or finishes in the top four he retains the title regardless of where Fernando Alonso places.
* Alonso requires a podium finish to stay in contention. If the Spaniard wins he needs Vettel to come fourth or worse to take the title. A second place for Alonso would leave Vettel needing a top-seven finish, while third would leave Vettel having to come in the top nine.
* Current standings
1. Sebastian Vettel, 273 points
2. Fernando Alonso, 260