Sauber wants to ease Esteban Gutierrez into Formula One rather than throw him in the deep end with a last-minute race seat.
That was the explanation of team boss Peter Sauber on Thursday following the Mexican teen's disappointment about not being called up in Montreal to replace the ill Sergio Perez.
To official reserve driver Gutierrez's chagrin, he was not even summoned to Canada before his McLaren counterpart Pedro de la Rosa, 40, sat in for Perez.
"I understand the question, but we have a responsibility to Gutierrez," Sauber is quoted by Germany's Speed Week.
"It is important to bring him slowly towards Formula One," added Sauber, whose Hinwil based team is backed considerably by Mexican billionaire Carlos Slim's companies.