Nico Rosberg beat Mercedes teammate Lewis Hamilton to the quickest time of the day in second practice for the Bahrain Grand Prix.
After a subdued first 90 minutes of running in the afternoon, normal service resumed for the Mercedes duo when the night fell over the Kingdom.
Rosberg's best of 1:34.467 put him 0.115 seconds ahead of championship leader Hamilton, both running on Pirelli's soft tyres when they set their fastest laps.
Mercedes' closest challenger was again Ferrari, with FP1 pace-setter Kimi Raikkonen finishing in third position, albeit over half a second behind Rosberg.
Both Hamilton and Raikkonen are under investigation for failing to leave the pitlane correctly.
Teammate Sebastian Vettel finished in fourth, but the German was involved in an incident that triggered a red flag near the end of the session.
Vettel was joining the track as Sergio Perez was braking for the first corner, the Mexican hitting the Ferrari's front wing, which was damaged in the incident.
The Ferrari driver reported a problem with his braking, but sounded angry at Perez over the radio. The incident is under investigation by the stewards and Vettel, who apologised to Perez later, could face a penalty.
Valtteri Bottas completed the top five for Williams, as the battle between his team and Ferrari looked extremely close.
Red Bull's Daniel Ricciardo was sixth fastest ahead of the Lotus of Pastor Maldonado and the Sauber of Felipe Nasr.
Daniil Kvyat and Felipe Massa completed the top ten.
Jenson Button had another poor session in the Honda-powered McLaren. The Briton, who did not even manage to set a time in first practice after being hit by electronic problems, was asked to park his car after just three laps.
McLaren had replaced Button's control electronics after first practice.
He returned to the track after some 50 minutes in the garage, but spent more time inside of it right after that as Honda checked data. He finished down in 19th position, seven places behind teammate Fernando Alonso.
|06||D. Ricciardo||Red Bull||1:35.449||+0.802||27|
|09||D. Kvyat||Red Bull||1:35.883||+1.236||23|
|14||C. Sainz||Toro Rosso||1:36.471||+1.824||32|
|15||N. Hulkenberg||Force India||1:36.805||+2.158||30|
|16||M. Verstappen||Toro Rosso||1:36.917||+2.270||26|
|17||S. Perez||Force India||1:37.062||+2.415||33|