MELBOURNE, March 16 (Reuters) - Nico Rosberg ended two years of frustration when he climbed onto the Formula One podium for the first time at Sunday's Australian Grand Prix.

The 22-year-old German kept his cool during a chaotic race at Albert Park to finish third in his Williams behind Briton Lewis Hamilton and compatriot Nick Heidfeld.

Rosberg, whose father Keke won the world championship in 1982, finished fourth at last year's Brazilian Grand Prix but said making the podium was the highlight of his career.

"Being on the podium in Formula One is a really great feeling," he told a news conference.

"It's been a while since I have been here and it's great for the whole team as they have been working hard over the
winter.

"They have done a good job and made some real progress."

Rosberg made his Formula One debut in 2006 and immediately served notice of his talent when he recorded the fastest lap during the race, the youngest driver ever to achieve the feat.

He finished 17th in the championship standings in his rookie season but jumped eight places to ninth in 2007, scoring points in seven races.

He qualified seventh for Sunday's Australian Grand Prix but overtook three cars to move into fourth by the end of the first lap.

Rosberg got as high as second after 20 laps before he took his first pit stop then fought off a late challenge from former world champion Fernando Alonso and Hamilton's team mate Heikki Kovalainen to snatch a place on the podium.

"I gave everything I had today, but it was a tough race on a street circuit in the heat which didn't make it easy," he
said.

"The team deserves my thanks for this great result, and it really encourages me to feel that I can grow with Williams.

"It's a big step forward for the whole team. I think we have a solid car to start the season with.

"We're hoping to have nice developments through the season - a lot of things we haven't been able to put on the car yet - and I think we can have a good year.

"We can't get too excited because we need to wait a few races to see where we are exactly but still I think we're in
quite a good position."

(Editing by John O'Brien)