F1: Nico Rosberg breaks 2015 win drought to lead Mercedes one-two
Rosberg has been a frustrated bystander while Mercedes teammate Lewis Hamilton claimed three of the opening four races of the 2015 campaign, but was never headed after starting from pole at the Circuit de Catalunya.
Hamilton finished second, prevailing in his own private battle with Ferrari's Sebastian Vettel, a poor start and botched first pit stop ending any hope of challenging Rosberg.
Britain's Hamilton had to adopt a three-stop strategy, "plan B" as his engineer relayed, to get the better of Vettel and has a 20-point lead over Rosberg in the championship race.
Vettel is a further 11 points adrift after finishing a distant third, over 45 seconds behind the winner.
Fernando Alonso's return to his home track, scene of his worrying crash in pre-season testing, ended in what he described as "scary" fashion when the brakes gave out on his McLaren-Honda.
Read: Alonso airlifted to hospital after testing crash
It was left to his pit crew to bravely bring the car to a halt as he was forced to retire.
"I had no brakes for the whole in-lap, and for the pit stop it was even less," admitted the Spaniard.
Vettel's teammate Kimi Raikonnen finished fifth, sandwiched between the Williams pair of Valtteri Bottas and Felipe Massa in fourth and sixth.
Daniel Ricciardo (Red Bull), Romain Grosjean for Lotus, Carlos Sainz Jr. (Toro Rosso) and Daniil Kvyat (Red Bull) rounded out the points scoring positions.
It was Rosberg's ninth career F1 win and a big relief after Hamilton's dominant end to the 2014 season to claim the title and his strong start this year.
"It was a perfect weekend," said Rosberg. "Perfect to be on pole and then to win the race like this. And, finally, I got a perfect start. It's been a long time coming."
With Vettel so far off the pace, despite edging ahead of Hamilton at the start, Mercedes look set to be on top for some time and it was their 14th one-two by its current driver pairing.
It equaled the run record of Ayrton Senna and Alain Prost at McLaren in their famous rivalry in 1980s. It was also the German constructors' 24th consecutive podium finish.