Mercedes boss fires parting shot at Rosberg

Nico Rosberg left F1 smiling and at the top of his game, but his shock departure hasn't left his former team so happy.

According to Mercedes non-executive chairman Niki Lauda, he left the team in the lurch by giving them no notice of his decision to leave the sport.

"What annoys me the most is that now Nico is telling us that he would have continued had he not won the world championship," Lauda told Germany’s Die Welt newspaper.

“This is something he could have at least hinted at when he signed his contract. In this case, we could have prepared a Plan B — we would have had to in order to be ready. But it is as it is.

“We all gave him the opportunity to become world champion in a fantastic car — and then he tells us he wants to retire.

“This has created a huge hole in this great working team. And we’re left looking dumb.”

Lauda, who won the F1 title three times, said that for him, defending your championship was the pinnacle of the sport.

"(Back in my time) I definitely wanted to defend my title. It was a challenge to have No. 1 on the car and to beat the opposition again," the 67-year-old said.

"In fact it was the most important thing to defend the title. You only wanted to be champion to do that.

"Nico chose to go down a different path, he always wanted to. The problem is he never gave any signs that these were his plans. This is why it took us by surprise."

Lauda isn't the only one firing shots at Rosberg following his retirement, after teammate Lewis Hamilton had a go at him immediately after the big announcement.