For the BMW WilliamsF1 team the opening day of practice for the 2005 Malaysian Grand Prix would see both drivers finish in the top ten with Nick sixth and Mark tenth. On a day that would see temperatures hit the mid thirties the teams had to cope with their first use of engines that weer seeing their second Grand Prix weekend.

The WilliamsF1 team had taken the decision to change Nick's engine as he did not finish the race in Australia. Technical Director Sam Michael had spoken about this subject to the media indicating that there were benefits from either both keeping the existing engine and replacing it. Both drivers would spend the session collecting information prior to Saturday's qualifying.

At the end of the session the quickest times would be taken by those drivers who did not have to worry about conserving their engines, drivers such as Ricardo Zonta, Pedro de la Rosa, and Red Bulls Vitantonio Liuzzi. These there would finish in this order at the end of the session. Zonta would set a time of 1m:34.092. All three drivers were Michelin supplied, with Michelin tyres again seeming to like the hot conditions. With engines having to last for two Grand Prix in 2005, most race drivers opted to run as little as possible in this the first practice session of the weekend.

The 60-minute session was dominated by the test drivers who do not have such engine concerns. These three drivers would complete over fifteen laps each while others would limit their amount of track times.

In fourth was Ferrari's Michael Schumacher, who would complete thirteen laps. BAR's Jenson Button was fifth fastest. Team-mate Sato would spin at Turn one, finishing the session thirteenth fastest. Both BAR drivers had new engines for the race after having decided to pull out of the Australian Grand Prix.

The McLaren's of Kimi Raikkonen and Juan Pablo Montoya were in seventh and eighth. Felipe Massa was ninth fastest in his Sauber Petronas ahead of Mark Webber.