Timo Glock has revealed he is disappointed by the departure of his Toyota race engineer Francesco Nenci.
The German driver is working with a new engineer beginning at the Nurburgring, Juan Pablo Ramirez, who joins from the Cologne based team's testing unit.
"He made a very good impression on me during the winter, but tests are not race weekends," Glock told Germany's Auto Motor und Sport.
"I was very content with the cooperation with my engineer," he added.
It is believed Nenci departed after disagreements with Toyota's technical management. "He understood me completely," the disappointed Glock explained.
"When I told him something about the car, he knew immediately what I wanted."
Red Bull, meanwhile, confirmed that Geoff Willis has departed the Milton Keynes based team because his role as technical director became redundant.