Rosberg is chasing his fifth win in a row after starting the season triumphantly in Australia to follow the three victories he racked up at the end of 2015.
Hamilton, the triple world champion who finds himself behind his German teammate in the standings for the first time since 2014, is on for a hat-trick after winning in Bahrain for the past two years.
The Briton is the favourite at a circuit that has yet to witness a Rosberg victory but Ferrari, who roared into the lead at the start in Melbourne with Sebastian Vettel followed by Kimi Raikkonen, also fancy their chances.
Had the race not been halted by Fernando Alonso's massive crash, with the McLaren driver now rested and raring to go again, Ferrari might have won and they certainly narrowed the gap to the champions.
In Melbourne last year, Mercedes finished one-two with Vettel third and 34 seconds off the pace. This time, Vettel was just 9.6 seconds behind Rosberg and 1.5 adrift of Hamilton.
Sunday's race at the Sakhir circuit, in the desert sands south of Manama, could be even closer.
"Bahrain is a track that should suit Ferrari, so we expect even smaller gaps and a very close match this weekend," said Mercedes motorsport head Toto Wolff.
"There are going to be weekends where we're a few seconds up the road from Ferrari, races where it's wheel to wheel and races where they might be ahead. We really don't know -- and that's exciting," said the champion.
"It's been entertaining on the track for the past two seasons there, so more of the same would be great."
With Formula One reeling under a wave of negative headlines, despite a thrilling season-opener, there are plenty in the paddock sharing his view.
The new qualifying format has been widely panned while fans are up in arms about the increasing drift away from free-to-air broadcasts in the European heartland.
Negative comments from the sport's 85-year-old commercial supremo Bernie Ecclestone about what is served up on Sundays, as well as mounting driver frustration about governance and future regulations, have only fuelled the fire.
Saturday qualifying is unlikely to provide much of a lift, with the sport's decision makers agreeing that the new format had not worked but still opting to give it a second chance.
"We haven't found the right format with this change and it's hard to see how it might be more entertaining for the fans this weekend in Bahrain," said Wolff.
The race itself could be a different matter, however.
Two years ago, Hamilton and Rosberg served up a thriller for the ages under the floodlights.
Last year Raikkonen finished just three seconds behind Hamilton after overtaking Rosberg. More of that would certainly help lift the gloom.