Many expect to see Barrichello (left) and Button (right) on the podium again
Only rain can stop Brawn GP duo Jenson Button and Rubens Barrichello in the Malaysian Grand Prix, their rivals say.
The pair occupied the top two places on the grid before finishing first and second in their debut race in Australia and rivals fear a repeat this weekend.
"If it doesn't rain they should win. If it does things might look different but rain's the only chance we all have," said Williams driver Nico Rosberg.
BMW Sauber boss Mario Theissen said their cars are "in a different league".
"The true performance came out in qualifying and in the first one or two laps in the race," he added.
"After that I think they didn't really exploit their potential. I don't see a chance to go at that pace."
Red Bull driver Mark Webber agreed, saying: "Brawn are on another level, obviously, and will be so for definitely this event and then we'll see what happens in China."
Button, whose win last weekend was only his second in 154 career starts, played down talk that his team is already beyond reach.
"It's difficult to say after one race, really, that we're unbeatable," he said.
"Red Bull were obviously quick, quicker than what we expected in Melbourne. I didn't think that they would be the team that would be up at the front. I also think that Ferrari will catch up, they always do.
"Those teams are the teams for me that are going to be competitive going forward and also BMW.
"It seems to be very close, we seem to have a slight advantage and then everyone is close and in the mix. It makes it exciting and I think different people will stand out in this race."