Pastor Maldonado put Lotus on top of the timesheets on the opening day of Formula One testing in Barcelona.
The Venezuelan had a troubled start to the day, with two stoppages due to sensor problems early on his Mercedes-powered E23 in the morning, but had a trouble-free remainder of the session and finished as quickest with a time of 1:25.011, set with soft tyres less than an hour from the end of the session.
Maldonado's closest challenger was Kimi Raikkonen, as Ferrari continued to show strong form with its new SF15-T.
The Finn had a good day and managed over 70 trouble-free laps, building on its Jerez performance.
Daniel Ricciardo finished third for Red Bull, the Australian covering 58 laps after a slow start to the day.
Sergio Perez joined the session in the afternoon, replacing Pascal Wehrlein in the 2014 Force India, and posted the fourth fastest time after 34 tours.
The morning's pace-setter Felipe Nasr finished in fifth position for Sauber, the Brazilian's work being hampered by his crash with the Williams of Susie Wolff one hour into the afternoon session.
Wolff, in her first outing with the new Williams, did return to the track with just 17 minutes to spare, but still managed a solid 86 laps on the day. Nasr also returned to action, but brought the test to a halt when he stopped out on track at Campsa near the end.
Wolff finished as 10th fastest, nearly four seconds off he pace.
Toro Rosso's Max Verstappen was the busiest man on track, with over 90 laps completed on his way to the sixth quickest time ahead of Jenson Button, who only managed 21 laps before his McLaren suffered an issue with its Honda powerplant that ended his day prematurely.
Wehrlein finished eighth in the Force India, and ninth in the Mercedes, which he drove in the afternoon.
Teammate Nico Rosberg is scheduled to drive tomorrow, but the German had to rest today to recover from inflamed nerve in his neck.
|3.||Daniel Ricciardo||Red Bull-Renault||1:25.547||+0.536||59|
|4.||Sergio Perez||Force India-Mercedes||1:26.636||+1.625||34|
|6.||Max Verstappen||Toro Rosso-Renault||1:27.900||+2.889||93|
|8.||Pascal Wehrlein||Force India-Mercedes||1:28.329||+3.318||32|