Sauber is seeking a second reserve driver that will be available when Marcus Ericsson is not present at the circuit. The Swede was confirmed as the team's third driver in September, when it announced that Antonio Giovinazzi would partner Kimi Raikkonen in 2019.
Soon after the announcement, Ericsson validated that he signed a deal with Schmidt Peterson Motorsport to race with it in IndyCar next year. Sauber is now looking for a driver to fill in for Ericsson when the two racing series collide in 2019.
There are eight clashes between the F1 and IndyCar schedules next year, but also other weekends where it would make little sense for Ericsson to attend an F1 race just to be on standby. Former Sauber racer Pascal Wehrlein has been linked with the role.
"Honestly we never spoke about this," Vasseur told Autosport Brazil. "And if Wehrlein did the simulator role for Ferrari I think he would stay in the factory. OK, Monza and Monaco you can do it.
"The strategy for me would be alongside Marcus to try to invest more in a young one, to try to prepare for the future. It will be much more this philosophy than anything else. But now it's quite difficult to find someone with 40 [superlicence] points!"