The Formula One Malaysian Grand Prix is a very demanding race, both for the drivers and the cars. Not only is there the humidity and heat to contend with--the drivers lose more than 6 pounds in sweat--but torrential rain can be, and often is, a problem. And there’s a good chance we’ll see some of the wet stuff this weekend.

The current forecast for Sunday’s race is a peak temperature of 93 degrees F (34 degrees C), humidity levels at 63 percent and wind speeds low. There is also the strong chance of a thunderstorm. Similar conditions are expected for Saturday’s qualifying.

Tire supplier Pirelli has brought its full wet tires just in case. Otherwise, teams will be using P Zero Orange hard and P Zero White medium, the two hardest compounds this year. This is to cope with the abrasive asphalt of Malaysia’s Sepang circuit; tire degradation will be a key issue during Sunday’s race.

After today’s practice session, it was clear Mercedes AMG will be the team to beat, though Ferrari and Red Bull Racing weren’t too far off the pace. Mercedes’s Nico Rosberg was the quickest during practice, followed closely by Ferrari’s Kimi Räikkönen and Red Bull’s Sebastian Vettel. Fourth quickest was Rosberg’s teammate Lewis Hamilton while Räikkönen’s teammate Fernando Alonso rounded out the top five.

Going into the weekend, Mercedes AMG’s Nico Rosberg sits on 25 points in the Drivers’ Championship while McLaren’s Kevin Magnussen and Jenson Button have 18 and 15 points respectively. In the Constructors’ Championship, McLaren leads with 33 points versus the 25 of Mercedes AMG and the 18 of Ferrari.

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