Sauber won't debut its 2016 car until the second pre-season test in early-March, Autosport reports.
The publication claims the Swiss team have delayed the debut of its C35 due to a "late change to the grand prix calendar", rather than financial or development concerns.
Sauber will however run at the opening four-day test which begins on February 22, but with a modified version of its '15 car, updated with its '16 livery.
Teams were put under increased pressure to have their cars ready earlier than originally scheduled after the opening race was brought forward two weeks to March 20.
That meant pre-season testing, which has been cut down from 12 days to just eight, was also brought forward.
