Heavy rain deluged the Sepang circuit on the eve of practice for the Malaysian Grand Prix, providing good and bad considerations for the teams and drivers eager to return to action after Melbourne last weekend.

Renowned for its flash storms that have the potential to flood its ciruit, Kuala Lumpur delivered on Thursday, with track and paddock under water in a matter of minutes, but the extreme conditions provided at least glimmer of hope for those hoping to upset the formbook on Sunday.

Left to scrap over the minor places in Australia, much of the field sees the likely return of the rain as their best chance of battling with and, given the newcomers lack of wet weather testing, even beating the Brawn cars of Jenson Button and Rubens Barrichello.

"If it doesn't rain, then Brawn Grand Prix should win but, if it does rain, then things might look a little bit different," Williams' Nico Rosberg ventured, "But the rain is the only chance that we all have, I think, to change that."

"When it's wet, it makes it more of a lottery for everyone - it becomes more of a challenge for everyone," world champion Lewis Hamilton elaborated, "It's not necessarily the fastest cars that can win, it's who can keep the car on the track and who is in the right place at the right time, so anyone from the back can have the same opportunity as the ones at the front."

Thursday's rain increased fears that the grand prix may be the victim of unprecitable weather over the weekend, not least on race day, when the proposed 5pm start could see the usual hot and humid conditions switch to the frequent scattered thunderstorms that tend to roll in at around that time.

For teams like Toro Rosso and Brawn, which only got their 2009 cars on track late in the pre-season, wet weather running is something of an unknown.

"I think if it rains like this we will need to organise a boat race," Toro Rosso's Sebastien Bourdais opined, "We don't even know what this car is like in the rain, so I don't think we can really give an answer to this."

Melbourne race winner Jenson Button, meanwhile, admitted to having changed his views on wet races since Honda morphed into Brawn.

"If it's raining like that, it's about keeping on the circuit, and I've struggled with that in the past couple of years in the wet," he conceded, "But I'm not too worried about that.

"The last two years, we've come to circuits hoping for rain because it throws a bit of excitement into the race for us because we would normally be hanging around at the back. But, here, when you've got a quick car, you obviously want it to be dry and you don't want any safety cars, you don't even want a breath of wind.

"So, for sure, I would rather it was just dry this weekend but, looking at the weather forecast, it's going to be storms in the afternoons and, obviously, it's a five o'clock race. It makes it more difficult and a bit more challenging for sure, but we'll take it in our stride and, hopefully, have a good car in the wet.

"We haven't tested in the wet yet with our car, but it's a good car and we've just got to hope it works. The only thing we've got to work out is the front wing angles and what-have-you, because previous cars we've had we've had to adjust massively for the wet conditions, so hopefully we're going to have some wet running before the race."