Pascal Wehrlein could be set to miss the start of winter testing in less than two weeks.
Wehrlein, 22, is switching to Sauber for 2017 from Manor, but at the Race of Champions event in Miami last month, the young German suffered a rollover crash.
He is now reportedly recovering from a minor neck injury.
"The Italian Antonio Giovinazzi is having a seat fitting at Sauber," reports Blick. "The Ferrari reserve driver will perhaps test in Barcelona as Wehrlein is yet to receive the green light from doctors."
The seat fitting could also be useful for later in the season, with the Swiss newspaper claiming that 2016 GP2 runner-up Giovinazzi could drive the Sauber during some Friday practice sessions in 2017.
