Michael Schumacher on Friday warned that Mercedes is unlikely to be setting the pace in Formula One for some time yet.
The W01 is consistently named among the quickest four cars in 2010, and with a big upgrade due at Barcelona next month, the team's optimism about joining the ultimate pace has been high.
But despite the silver single seater looking almost as quick as Lewis Hamilton's pace-setting McLaren at Sepang throughout the initial day of practice, Schumacher said: "It (getting on the pace) might take us a bit longer than we hoped for."
The seven time world champion spent much of the Australian GP behind Toro Rosso's Jaime Alguersuari, and he says the car is "aerodynamically very sensitive".
"We have a problem when we're driving behind the others," Schumacher is quoted as saying by Bild newspaper.
Team boss Ross Brawn replied: "If we soon have more performance, then Nico and Michael will be able to overtake. It's all about the performance.
"I wouldn't say that our car is more sensitive than the others," insisted the Briton.