SEPANG, Malaysia, March 22 (Reuters) - Nico Rosberg came back down to earth in qualifying for the Malaysian Grand Prix on Saturday, a week after celebrating the first podium finish of his Formula One career.

The Williams driver will start 16th at the Sepang circuit, a far cry from his stunning third place finish at the
season-opener in Australia last week.

"I can't believe how it went today," said the German.

"I came here from a podium finish a few days ago and now I qualify 16th, although I thought my last flying lap was pretty good."

Rosberg, whose father Keke won the world championship in 1982, said the smooth Sepang surface did not suit the Williams.

"Our car doesn't seem to like the new asphalt they laid on the track at all. It's just too smooth and it doesn't make our tyres work properly, so I am just sliding everywhere," he added.

Ferrari's Felipe Massa and Kimi Raikkonen claimed the top two places on the grid for Sunday's race, with McLaren's Heikki Kovalainen and Lewis Hamilton in third and fourth spots.

Rosberg's team mate Kazuki Nakajima was 18th but will start from last place after being handed a 10 place penalty for an infringement in Melbourne last week.

"It will be tough tomorrow starting from this position, but our car should be better in racing conditions," said Rosberg.

"And maybe some rain might help us."

(Editing by Alan Baldwin)