Sauber have parted company with Technical Director Jörg Zander in a continuation of their restructuring.
The Swede completed one hundred and forty-eight laps on Thursday as he drew to a close his pre-season testing programme.
The Swede was one of only three drivers to complete more than one hundred laps on Tuesday.
Frederic Vasseur insists Sauber need a big jump in performance in 2018 to fight in the midfield, and insists most of this will need to come from the aerodynamic department.
Sauber F1 Team Boss Monisha Kaltenborn is believed to have cut ties with the Swiss squad today.
Andrew Green, Paul Monaghan and Jörg Zander speak to the media at the 2017 Monaco Grand Prix Thursday Press Conference ahead of this weekend.
After financial problems hindered their 2016 Formula 1 season, Sauber F1 Team are focused on establishing themselves as a midfield team for 2017.
Sauber’s Technical Director was happy with the performance of the C37-Ferrari during the opening day of pre-season testing on Monday.
Jorg Zander believes Sauber now have the strength and stability to fight in the midfield pack this year.
Jörg Zander has returned to the Sauber F1 Team as Technical Director, nine years after leaving the Swiss team when under the ownership of BMW.