Boss Frederic Vasseur is refusing to say who will drive for Sauber in 2018.
According to some, the Swiss team could do a clean sweep and oust both Pascal Wehrlein and Marcus Ericsson.
A frontrunner appears to be Charles Leclerc, the GP3 and now Formula 2 champion who is strongly backed by Sauber engine partner Ferrari.
But Sauber boss Vasseur insisted in Mexico: "We signed a contract for the supply of engines, not the supply of a driver.
"We are talking to Ferrari," he confirmed.
He denied some of those talks are about turning Sauber into a second Haas-like Ferrari ’B team’.
Vasseur said: "We are already well on our way with the new car and it’s difficult to use parts from another constructor.
"Additionally, we have a lot of knowledge at Hinwil and do not want to lose that. We know how to develop a car.
"In the short term it would be easy to buy all kinds of Ferrari parts, but in the long run it would undermine the capabilities of our own team," he added.
However, another rumour is that Ferrari’s other junior, Antonio Giovinazzi, is also in the running, while Sauber might prefer to keep at least one of its current drivers on board next year.
It is believed Ericsson, with close ties to Sauber’s owners, would be the favourite.
"Next question," Frenchman Vasseur smiled.
"We hope to have an answer to that soon, but we know where we stand. The drivers are currently not our priority.
"More important is that we build a better chassis," he added.
What Vasseur will say, however, is that Ericsson’s backers do not mean he will definitely stay at Sauber.
"No, the financial aspects do not matter here," he said.
"We have a long term plan for the team and a healthy budget, so we do not connect next season with the money that a driver brings."