Lewis Hamilton and Nico Rosberg hammered home Mercedes' early season dominance on Friday when they set the fastest times in both opening practice sessions for Sunday's floodlit Bahrain Grand Prix. Hamilton, the winner in Malaysia last weekend, clocked 1min 34.325sec in the second spell having also roared away to the leading time in the afternoon of 1min 37.502sec. World championship leader Rosberg, who won in Australia, was in second spot thanks to a time of 1min 37.733 in the first session and, just like his teammate, was then untroubled under the lights with a time of 1:34.690. Ferrari's Fernando Alonso, a three-time winner at the dusty Sakhir circuit, was third-fastest overall with 1:35.360, more than a second behind Hamilton. Sunday's race will start at 1500GMT and Hamilton said the drop in temperatures as the sun sets in the desert will keep the teams on their toes. "The track temperature was 38-40 degrees (Celsius) and then this afternoon was a lot cooler, about ten degrees, so it's just really not trying to panic and react to the change," said Hamilton. "We struggled a bit on the tyres as everyone did." Rosberg said he was looking forward to racing at night. "It's spectacular. Even on track it's very impressive. It's good, especially for TV viewers. It's going to be great to watch," said the German star. "Visibility-wise it's very similar to Singapore. It's a bit more difficult in the dark with the glare." Defending champions Red Bull, who have struggled with the new technical changes for the 2014 season, had toiled in the afternoon period with four-time champion Sebastian Vettel down in 10th place. His Australian teammate Daniel Ricciardo was in 14th place, but both men enjoyed a considerably stronger evening session. Ricciardo, who was disqualified in Australia and failed to finish in Malaysia, took the fourth fastest spot overall on 1:35.433 while Vettel edged up to seventh, 1.281sec behind 2008 world champion Hamilton. "It was a solid day for us and we didn't have any problems with the car. We’re still learning a lot in terms of reliability and car set up, so it's important to do laps and not to have any problems," said Vettel. Alonso said that racing at night added to the challenge in the desert. "After many daytime races, it was really strange to be running here in the dark, even if it was not very different to the other night time races, so we just have to get used to it," said the Spaniard. "From this aspect, today was very useful to learn about the behaviour of the tyres and the car." Felipe Massa, the Brazilian with two career wins in Bahrain during his Ferrari days, was the top Williams performer. His time of 1:35.442 was good enough for fifth place with 2009 world champion Jenson Button, taking part in his 250th Grand Prix, sealing sixth fastest in the leading McLaren in 1:35.528. After Vettel, the top 10 was completed by Russia's Daniil Kvyat in a Toro Rosso, Denmark's Kevin Magnussen in the McLaren and Force India's Sergio Perez. Force India's Nico Hulkenberg, who had been fourth quickest in the afternoon, slipped back to 13th in the evening. The Lotus duo of Pastor Maldonado and Romain Grosjean were only 17th and 18th respectively while Marussia and Caterham filled the last four spots. Source: AFP