An unwell Lewis Hamilton will sit out the remainder of the day's action at the Circuit de Barcelona-Catalunya, Mercedes has confirmed.
Hamilton completed 11 laps during the first couple of hours of running on the first day of the second pre-season test in Spain, before the team confirmed that the World Champion was not well enough to continue.
Hamilton will be replaced later on today by test driver Pascal Wehrlein, who had taken to the circuit earlier on as part of his planned running with Force India.
Wehrlein had racked up 10 laps in the squad's 2014 car, the VJM07.
Hamilton is due to return to the cockpit of his Mercedes W06 Hybrid on Saturday.
Sergio Perez will replace Wehrlein in the Force India this afternoon.