MANAMA - Lewis Hamilton and Nico Rosberg put Mercedes' early season dominance to its first true test Sunday at the floodlit Bahrain Grand Prix on a track where both drivers have always struggled.Hamilton, the 2008 world champion, swept to victory from pole in Malaysia last week ahead of Rosberg who clinched the championship opener in Australia.But despite their lofty positions in the 2014 title race, the dust and heat of the troubled Middle East state have often choked the pair's ambitions. Hamilton's best finish at the Sakhir track was second in 2007 while Rosberg has never made the podium with his storming drive to pole position in 2013 yielding a poor ninth place finish. His best result remains a humble fifth."I've finished on the podium there a couple of times but, for one reason or another, I've never managed to get the win," said Hamilton, whose victory at Sepang followed a retirement in Australia. "Until last week it was the same story for me with Malaysia, so fingers crossed this can be the year of breaking those cycles."We know it's going to be tough to maintain our current form, particularly at a circuit where every team has had so much running time in testing over the winter, but I'll be pushing hard to keep those results coming."Rosberg is the championship leader after two events and enjoys an 18-point cushion over Hamilton. But he too is aware that Bahrain, which rarely features standout duels, has not been a happy hunting ground. "The first two races have been a great start to my season and I'm already looking forward to being back in the car and carrying on that momentum in Bahrain," said the German."It's a great track and I really enjoy driving it. I've never had much luck on race weekends here, but it's definitely the one I'm best prepared for this year. "We may be leading both championships at the moment but our rivals are breathing down our necks, so we need to stay focused and keep doing our job calmly and professionally."While Mercedes have shone in the early weeks of the season, it's been a tale of relative woe for world champions Red Bull.Four-time champion Sebastian Vettel failed to finish the season-opener in Australia before grabbing third place in Malaysia. He sits seventh in the title race while teammate Daniel Ricciardo has yet to get on the scoreboard as Red Bull wilt in the shadow of Mercedes.Vettel has looked as unsettled as his car so far in 2014 as he lies 28 points off Rosberg and with even Nico Hulkenberg of the unheralded Force India team ahead of him.He has even lambasted the new low-noise hybrid engines as "shit" while his team has grappled with a raft of technical tweaks to the championship. Even though the German star has won the last two races in Bahrain, his team boss Christian Horner is not holding out a great deal of hope that Mercedes' stranglehold will be broken this weekend. "I think their advantage in Bahrain will possibly be larger than it was in Malaysia, because that is quite a power dominated circuit," Horner told www.autosport.com.Ferrari's Fernando Alonso, who finished fourth in Australia and Malaysia, has proved the master of the desert conditions, winning in 2005, 2006 and 2010. But even his trademark rock-solid self-confidence has been dented by seeing both Rosberg and Hamilton record runaway wins of over 35 seconds in the first two events. "We can expect a tough race, as some of the competition is very strong and we will have to raise our game to close down the gap as quickly as possible," said the Spaniard. Away from the track, the race has once again become the focus of the country's long running civil strife. On Tuesday, Bahrain's Shiite opposition called separate rallies to protest the staging of the race. Demonstrations have been held during the weekend every year since 2011 by opponents of the ruling Sunni Al-Khalifa dynasty in an attempt to highlight pro-reform demands.