George Russell says he has been given "no promises" by Mercedes about a race seat with the works team for 2022.
As Williams' likely back-of-the-grid 2021 car was revealed, Russell said the team's goal for this season is to "not be last" after a battle with Haas and Alfa Romeo.
"The new Ferrari engine will certainly make those teams faster, but on the other hand we have worked well over the winter," he said.
"Investments have been made, we have some good new people, relations with Mercedes are expanding and there is more to come."
"At the moment my head is completely with this team," said Russell, referring to Williams.
"By the middle of the year we should be getting an idea of how things will proceed for me. I am concentrating on my performance and making progress and then my chance will come at some point.
"But there are no promises for 2022," the Briton insisted.
"It can be argued that 2022 would be the right moment for a change, but as I said, it's not up to me to decide. If there is an opportunity like there was in Bahrain last year, I will of course grab it with both hands."
Russell said he is happy to have the full backing of Mercedes and Wolff.
"Toto told me that I am part of the future at Mercedes and I take his words at face value," he said.