Just as it had in Bahrain, when the pair staged another spectacular duel, their fight developed into one of differing strategies. After Hamilton kept the lead in the first stints, Rosberg changed to the hard Pirelli tyres as Hamilton took another set of mediums. Rosberg really made the hards work for him, setting up the dramatic finale to the 66-lap race.
Called in earlier than he wanted on the 43rd lap - and after staying out for one more than the team requested - Hamilton had to fight to the finish on a set of hards as Rosberg, who stopped on the 44th lap, went back to the faster mediums.
Race winner Lewis Hamilton (GBR) Mercedes AMG F1 celebrates in parc ferme. Formula One World Championship, Rd5, Spanish Grand Prix, Race, Barcelona, Spain, Sunday, 11 May 2014. © Sutton Images
Almost straight away Hamilton found himself struggling on the harder compound, and its tendency to grain more than the medium. A lead of 4.8s on the 46th lap was steadily reduced - it fell to 4.6s, 3.6s, 3.7s, 3.1s, 2.3s and 2.0s over the six ensuing laps before he found a better way to preserve his tyres and reopened it to 2.7s by the 54th lap.
Rosberg was relentless in pursuit however, and charged once more. By the 56th lap Hamilton's lead was back down to 2.1s, then 1.8s, 1.4s and 0.9s, before Hamilton gained precious breathing space by opening it back up to 1.3s by the 60th.
Still Rosberg kept coming, and down the gap came all over again. With three laps to go it was 0.9s, then 0.7s. They went into their final lap separated by only 0.6s, nose to tail, with everything to play for and Kimi Raikkonen's Ferrari to lap as they sped into Turn 1. Hamilton got by the red car before the corner, but so did Rosberg.
Through Turn 1 Hamilton kept it together, then through Turn 3, and gradually Rosberg's hopes faded. He needed, he admitted, just one more lap to launch an attack. To the relief of the entire Mercedes crew, including overall boss Dieter Zetsche, both of the Silvers Arrows made it across the finish line intact, still separated by those six-tenths of a second. It was their fourth consecutive one-two finish.
And what a crushing demonstration it was for the Anglo-German cars. Daniel Ricciardo figured third place was the best position possible for Red Bull and indeed took the final podium slot legally for the first time after a strong run, but he was 49s behind Hamilton by the finish.
The Milton Keynes team got a big boost as a feisty drive from 15th-place starter Sebastian Vettel, allied to clever deployment of a three-stop strategy, brought him past the dogged Williams of Valtteri Bottas and into fourth with three laps to run.
A three-stopper also worked for Fernando Alonso, who played second fiddle to two-stopping Ferrari team mate Raikkonen for much of the race. The Spaniard moved by the Finn with three laps to go, but his sixth place was very distant - Hamilton's Mercedes was 87.7s up the road, and had indeed lapped the seventh-placed Raikkonen.
Romain Grosjean fought brake problems, which dropped him behind the Ferraris, to score Lotus's first points of the season in eighth, a mere second ahead of the dueling Force Indias of Sergio Perez and Nico Hulkenberg.
McLaren's Jenson Button and Kevin Magnussen were in the fight for midfield points most of the way, but just didn't quite have the pace to better 11th and 12th places, while a very disappointed Felipe Massa found a three-stop strategy failing to work out for him as he took 13th for Williams.
Daniil Kvyat was his usual forceful self but didn't have a car capable of better than the 14th he claimed for Toro Rosso on an afternoon when an exhaust problem rendered team mate Jean-Eric Vergne the first of two retirements.
Pastor Maldonado was given a five-second stop-and-go penalty for clobbering Marcus Ericsson's Caterham early on and wound up 15th ahead of the Saubers of Esteban Gutierrez and Adrian Sutil, who switched places on the final lap.
Behind them, Jules Bianchi won the Marussia battle with team mate Max Chilton and they comfortably beat Ericsson home. The Swede's team mate Kamui Kobayashi was the other retirement after his second brake failure of the season.
Hamilton now has 100 points to Rosberg's 97, with Alonso third on 49. Vettel is fourth on 45, with Ricciardo directly behind him on 39. In the constructors' stakes, Mercedes pull further ahead with 197 to Red Bull's 84, while Ferrari move ahead of Force India, with 66 to 57, and Williams overtake McLaren, 46 to 43.