Sebastian Vettel is only an "outsider candidate" for a Mercedes race seat in 2021.

That is the news from team boss Toto Wolff, who said he will not join Ferrari and McLaren in announcing Mercedes' 2021 lineup so far ahead of time.

"I don't want to pull the corset too tight in terms of timing," he told German media, "but we want to start the season first and let both drivers race freely.

"We also want to see how George (Russell) goes. We want to make this decision during the course of the summer," added Wolff.

Wolff has paid lip service to the notion of signing 2021 Ferrari refugee Vettel, but the German's chances actually do not appear to be high.

"Sebastian is of course a great personality and, with four titles, also one of the outstanding drivers of his generation," he said.

"He is an outsider candidate for us. First and foremost, we are looking at our own Mercedes stable. But I wouldn't say no to Sebastian in terms of talent and personality."

Wolff also responded to speculation about his own future, amid suggestions that he could team up with Lawrence Stroll to take over the Mercedes team.

"It's clear when there are no other headlines than the Aston Martin thing that it causes some waves," he insisted.

"But I am team principal and a shareholder and I have the best intentions to stay here."

However, Wolff added: "I don't want to become a team principal that goes from great to good without realising that he's maybe not adding as much to the team as he did in the beginning.

"There will come a time when I will do less and I want to be ahead of that moment. That is what I am thinking very carefully about now."