F1 driver Mark Webber says it's impressive Nico Rosberg's retired from the sport at the top of his game.

The German announced last week he'd called it a day at just 31 - five days after winning his first drivers' world championship with Mercedes.

"Absolutely," Webber said when asked whether Rosberg was in fact a worthy champion. "I was really happy for Nico, I thought he drove really well this year under immense pressure.

"It's been a long campaign for him, it hasn't just been 21 races. He's had over 80 races fighting for the championship against Lewis [Hamilton, Mercedes teammate]. Lewis has obviously got three and now Nico has that one that he's been fighting for for so long. 

"I'm really happy for him. I think Mercedes will miss him because technically I think he brings a lot to the programme as well. He's very fast, good at setting the car up and using the resources within the team."

Webber says Rosberg's young family was a factor in his decision - and that it's not that strange he's retired.

"He's got a little family now and, you know, racing drivers don't have to drive forever. That's just a given. People think there's a shelf life and drivers just run that out. That's not always the case.

"It's a sniff early but in terms of him wanting to do it, I wish him all the best."