Sauber's Felipe Nasr topped the times in the opening morning of Formula One testing at Barcelona as world champion Lewis Hamilton pulled out due to illness.
Nasr took to the top of the times in the Ferrari-powered C34 nearly three hours into the test with a best lap of 1:27.307 to finish ahead of the Red Bull of Daniel Ricciardo, who only set a laptime 40 minutes from the end.
Hamilton was forced to withdraw from the test after just 11 laps as he had a high fever, with Pascal Wehrlein, who was initially driving for Force India, switching to the Mercedes cockpit right before the lunch break despite Nico Rosberg being present at the track.
Sergio Perez will drive the Force India in the afternoon.
The McLaren team was also forced to end its day early after a promising start.
Jenson Button had managed 21 laps, but a problem with an energy recovery system meant the Briton will be unable to run in the afternoon, as the whole power unit needs replacing.
Kimi Raikkonen set the early pace for Ferrari, but the Finn dropped down the order as the session progressed and finished down in fifth position behind the Lotus of Pastor Maldonado and Max Verstappen in the Toro Rosso.
Lotus had a difficult start to the test when Maldonado stopped on track less than half hour into the session, the Venezuelan managing just five laps before his Mercedes-powered E23 came to a smoky halt.
When he returned to the track later, the Lotus driver's running was short-lived again, stopping with a sensor issue. The problem was solved quickly, however, and Maldonado managed over 40 laps in the morning.
Williams tester Susie Wolff made her debut at the wheel of the new FW37 and was the busiest driver with nearly 80 laps covered on her way to the eight quicker time, just ahead of Hamilton.
|2.||Daniel Ricciardo||Red Bull-Renault||1:27.363||+0.056||18|
|4.||Max Verstappen||Toro Rosso-Renault||1:27.951||+0.644||35|
|7.||Pascal Wehrlein||Force India-Mercedes||1:28.329||+1.022||38|