Formula One pace-setter Jenson Button on Thursday warned Malaysia's notorious downpours could decide this week's Grand Prix after winning the washed-out edition in 2009.
The McLaren driver said the fast-running Sepang circuit was a very different proposition to last Sunday's Australian Grand Prix, where he seized control of the new season with victory at Melbourne's parkland lay-out.
But he said Malaysia's frequent torrential rain was the unknown factor that had the potential to throw teams' plans into disarray, or even end the race altogether.
"It's so different to last weekend. It's very fast and flowing and it's very smooth compared to a street circuit," Button said.
"And it's one of those places where you really don't know what the weather's going to do. Previously when I won here the race was cut short because of a red flag. That's the thing, it doesn't just rain, it chucks it down.
"So if it does rain we hope we can continue racing because it's a great circuit."
Button's sole win at Sepang, near Kuala Lumpur, came when officials were forced to call off the Grand Prix mid-race when a tumultuous storm made the track undriveable.
Button, in the lead at the time of the stoppage, went on to win that year's drivers' championship.
On Thursday afternoon, sporadic heavy rain soaked Sepang as drivers visited the track. Free practice will start on Friday morning and the race begins at 4:00 pm (0800 GMT) on Sunday.
Ferrari's Fernando Alonso hoped cloudbursts could work in the favour of the beleaguered Italian team, whose car is widely perceived to be lagging McLaren and Red Bull, the defending constructors' champions.
"Here with a normal race maybe we'll finish further behind. Maybe with a more crazy race, or rain or something, we can finish in front," said the Spaniard.
After one race, Button leads the standings by seven points from Red Bull's Sebastien Vettel, who is aiming at becoming only the third driver in history to win three championships in a row.