Rosberg, who has sauntered to victory at each of the four races so far this season to establish a 43-point lead over Hamilton, was nearly three quarters of a second faster than his Mercedes team-mate yesterday.
Indeed Hamilton’s best lap at the Circuit de Catalunya was good enough only for third with Ferrari’s Kimi Raikkonen splitting the Mercedes pair. Sebastian Vettel, fastest in the opening session, was fourth quickest in the sister Ferrari.
Rosberg is bidding to win an eighth consecutive race - a streak which stretches back to last season - and one which would see him become only the second driver to win as many grands prix in succession in the modern era. He is currently tied with Michael Schumacher, while Vettel holds the record with nine.
The 30-year-old German has played down his incredible run of success, but should he take to the top step of the podium once more tomorow, both Vettel’s winning record, and more importantly the championship, will surely be at the forefront of his mind.
For Hamilton, who visited New York, Athens, Miami, Barbados and Monaco following the last race in Russia, he is without a win since his dramatic triumph in October’s United States Grand Prix - the scene of his third championship - now 200 days ago.
The Briton is due some luck, with car problems stalling the defence of his title, but a scruffy lap here in practice, forced him settle for third yesterday.
The second session in Barcelona as Formula One returns to Spain for the traditional start of the European season, was suspended for nearly 10 minutes after Briton’s Jolyon Palmer suffered a high speed tyre blow-out in the opening moments.
The 25-year-old, who on Thursday insisted he will see out the season with Renault despite suggestions he could be replaced by Frenchman Esteban Ocon, brought his car to a halt at turn one.
Meanwhile, Pirelli, the sport’s sole tyre supplier, has launched an investigation into the incident.
Elsewhere, Max Verstappen, making his debut for Red Bull after Daniil Kvyat was demoted to Toro Rosso, finished both practice sessions behind his new team-mate Daniel Ricciardo. Verstappen was eighth in the second session with Ricciardo sixth.